If we r not to do MBA without cat exams ???

There are various entrance exams apart CAT like SNAP, CMAT, MAT, NMAT, XAT, State level management entrance tests etc. These are the initial screening for MBA Entrance. You need to appear in these to get admission to MBA.

Yes cat exam is basic step for MBA

Hy,
you could give other MBA entrance exams like XAT , IIFT, NMAT , CMAT , CET and SNAP .

For these exams the extra you would have to do is brush up your GK which you will have to do for your CAT GD- PI round also.

Solve the past papers and follow any good general awareness website along with a few standard books which cover the important topics.

If you have work experience you could try the GMAT too.
All the best !!!
I wish you all the best.
Cheers !!