The profile surface equation and the meshing equation of a steel ball globoidal indexing cam with double-arc structure were deduced by using rotation tensor method and spatial engagement theory. The load distribution and connection expression of input torque and output torque were deduced applying hertz contact theory and deformation compatibility condition. It was acquired by example that the load distributed on each steel ball engaging in was different and the force on steel ball changed abruptly when steel ball was engaged in and out, the more steel balls were engaged in, the smaller force of each ball would be. 