Hello Sunil,

Here is the best books to prepare for NIMCET exam;

1. Excel With Objective Book For NIMCET. By J B Dixit, Ruchi Sharma, Ashish Mangal.

2. Upkars MCA Test. By A Team of Experts.

3. Arihant MCA Entrance Test (Self Study Guide) By Amit M. 

4. Mathematics General Aptitude Books. 

5. Barron's Military Flight Aptitude Tests. 

6. The Aptitude Test Workbook. 

7. Numerical Ability & Mathematical Aptitude.

Hope this will help you. All the best.