Will I get journal for Gap Check between solid body to solid body and part to part.

In a assembly there will be a so many movable parts. so I have to ensure suffiecient clearence between the constant part body to movable part body according to the STD gap dimension to get good output.will I get journal for this.

I suggest you search the NX help on the topic "assembly clearance" or "clearance analysis". NX has built-in tools for this, no journal needed.

Need to check for clearance API