This paper studies the xor branch numbers of diffusion structures, which uses the nonlinear transformations over the finite field GF(2). This paper gives the definition of the xor branch numbers of diffusion structures and the relations between it and the strength of a cipher against differential and linear cryptanalysis. Also, this paper has proven that the xor branch numbers of diffusion structures is about modulo 2ⁿ addition, and the modulo 2 addition is equal to that of the diffusion structure over the finite field GF(2), which 1 is substituted for the odd coefficient and 0 for the even coefficient and the modulo 2ⁿ addition for the modulo 2 addition. Consequently, this paper simplifies the computation problem of the xor branch numbers in this kind of nonlinear diffusion structure.