Bore's shape in electromagnetic launch usually involves coupled rectangle or quadrate, round and inverted arc at the present. But bore's shape of test assembly is major rectangle and inverted arc. In the paper the studies of simulation and test are carried on the bore of rectangle and inverted arc. The detailed comparison about the bore of rectangle and inverted arc were studied in current density distribution, induction gradient, contact pressure, contact state, structure manufacture and launching precision. The last test studies of both bore were carried on contact state and launching efficiency. We got a few of results about the bore's shape in electromagnetic launch. The results prove that the bore of inverted arc were better than the bore of rectangle in current density distribution, induction gradient, contact state and the accuracy of armature running. These can be foundation of different need in electromagnetic launch design.