Sir my age is 21+ my cast is hindu and I want to marry with muslim gir

you can marry under special marriage act, This is an important act for the court marriage & marriage registration of both the partners irrespective of their caste & religion.

No traditional marriage & rituals are performed during the marriage under this act. It takes around 30 days for the completion of the marriage. All inter-religion marriages are performed under this act. The approval of parents is necessary for the marriages under the SMA, 1954.