during iit admission they will check my 12th percentage... if i had get good rank in advance...so i can get admission or bcoz of 12th low percentage i will not get admission.
The percentage of class 12 is only a qualifying clause. You only need a certain minimum percentage to qualify for IIT. No matter how much you score past the minimum score it is not an advantage or disadvantage for you. If your rank is good in advance then your 12th class percentage will not be a hindrance in the way of your admission.