Can a boy marry to his aunt's sister's daughter(father's brother's wife's niece)

Law does not permit it.  You will be marrying your sister.  You both are sapindas as you have common ancestor.  Such marriages are unlawful according to Hindu Marriage Act. Your kids will be born with congenital defects, please save our nation from it.

First type the title properly. Aunt or Aunt's daughter ? Title says aunt. But your post says Aunt's daughter.

Also, this depends on the caste system in Hinduism. So, the answers to your question can ony be given on a generic basis.

The castes that follow Gotra system of the Seven Rishis of the past, have much stricter rules and methods.

SAPINDA as per hinduism happens when it is brother's daughter or mother's sister's daughter. 

But MUSLIMS practise sapinda. Boy marries his father's brother's daughter. As per hinduism, this is equal to marrying one's own sister.

But Muslims do not marry aunt's daughter. So, their rules are the REVERSE of Hinduism Rules.

So, in general, answers may be provided.

But, By aunt's daughter, whom do you mean ?

1.Father's Sister's daughter ?

2.Mother's Sister's daughter ?

3.Mother's Sister's sister-in-law's daughter ?

4.Father's Sister's sister-in-law's daughter ?

5. Father's brother's wife's Sister's daughter ?

6. Mother's brother's wife's Sister's daughter ?

As per hindu tradition, here is the answer ( General set. Not to be treated as answer if you belong to a caste that follows Gotra system of the Seven Rishis of the past )

1.Father's Sister's daughter ?-------------------Yes, permitted ( since her father is different gene pool )

2.Mother's Sister's daughter  ?------------------ NO. she is your sister. ( Shared genes of your mother's sister who has genes from the same father of your mother )

3.Mother's Sister's sister-in-law's daughter ?------------------ Yes. permitted.( since her father is different gene pool )

4.Father's Sister's sister-in-law's daughter ?----------------- Yes.permitted.( since her father is different gene pool )

5. Father's brother's wife's sister's daughter ?---------------  NO. To be treated as sister ( since her aunt is like your mother as she has married your father's brother )

6. Mother's brother's wife's sister's daughter ?--------------- Yes. permitted.( since her father is different gene pool )

ALL MEDICAL GENETIC DISEASE etc are taken out of proportion and blown to huge size in recent times.

The chart above has been in existence in India, for thousands of years and except for five out of one thousand children from such marriages, the rest are all healthy.

Choice is Yours. The chart above is the one followed in India for thousands of  years.

Earlier i typed the same title and message but updated some missing text

@hapling hand - Accroding to you how her and mine ancestors are in blood relation they are totally different 

If she is your aunt's NIECE ( her brother's daughter ), then YES, it is permitted

If she is your aunt's NIECE ( her sister's daughter ), then NO, it is NOT permitted

why is it permitted in aunt's brother's daughter case 

and why not is in aunt's sister daughter case

If there is custom (proven custom) that has attained legal sanction (as in some states, in some communities) then one can.

@Natrajan  - Accroding to this i agree this point but her father is related to different gene pool .Hence, why it is not possible then.

why is it permitted in aunt's brother's daughter case  and why not is in aunt's sister daughter case
 

AS PER HINDUISM's SCIENTIFIC KNOWLEDGE PRACTISED FOR GENERATIONS AND THOUSANDS OF YEARS, AUNT ( YOUR FATHER's BROTHER's WIFE ) IS EQUATED TO YOUR MOTHER AND UNCLE ( FATHER's BROTHER ) EQUATED TO YOUR FATHER.

SO, AUNT's BROTHER IS SIMILAR TO YOUR MOTHER's BROTHER --- SO YOUR MATERNAL UNCLE.

MARRYING DAUGHTER OF MATERNAL UNCLE IS PERMITTED SINCE YOUR FATHER's GENE POOL AND YOUR MATERNAL UNCLE's FATHER's GENE POOL ARE DIFFERENT. 

BUT AUNT's SISTER is equated to YOUR OWN MOTHER's SISTER.

SO, MARRYING THE DAUGHTER OF YOUR AUNT's SISTER IS LIKE MARRYING YOUR OWN SISTER.

Hope this clarifies.

@Natrajan  - Accroding to this i agree this point but her father is related to different gene pool .Hence, why it is not possible then.
 

ANSWERED ABOVE.

ok thanks close this query 

Nobody is here to close queries unless the admin moderator exercises his methods.

You just have to drop and exit.

This is for your information.

If you still need more details, go through link given below:

https://en.wikipedia.org/wiki/Cousin_marriage

Animals like you dont have brother sister.

The member has deleted the account.

Then who is my father's sister's husband's sister .(That is who is my aunt's sister-in-law)