Abstract: The clad plate of 2205/Q345C (stainless steel/low alloy steel) was prepared by vacuum symmetry block blank+thermal rolling method, and the influence of compression ratio on the interface microstructure, element diffusion, hardness distribution and shear strength were studied.The results show that 2205/Q345C clad plate interfaces combine well at different compression ratios.Decarburizing layers and carburizing layers exist near the interface of base layer Q345C and compound layer 2205, respectively.Decarbonburbed depth decreases and carburization layer depth increases with the increase of compression ratio.The proportion of the decarburization depth to the total plate thickness increases with the increase of compression ratio.Continuous diffusion of Cr, Ni elements occurs near the interface of the clad plate, and the atomic diffusion distance decreases with the compression ratio.Near the interface of clad plate, the hardness of stainless steel is the highest while that of carbon steel is the lowest.With increasing compression ratio, the hardness and interface shear strength of composite plate are improved, and the plasticity first increases and then decreases.The interface shear strength of 2205/Q345C clad plates with 3 compression ratios meet the requirements of the shear strength of ≥210 MPa in GB/T 8165-2008.