Abstract - In this paper, we classify and evaluate the involutory diffusion layer of 64-bit AES-like block ciphers based on the Hadamard matrices. Firstly, we calculate the number of fixed points in this layer. After that, we perform a practical investigation on the 4×4-bit Hadamard matrices in GF(2^4) and modify the number of XOR gates used to implement as described in [9] to choose a suitable matrix for constructing the involutory diffusion layer of AES-like block ciphers with 64-bit block size.