Abstract: Multi-layer stacking layer samples were prepared by double-wire and plasma arc additive manufacturing process on Q235 steel plate at different deposition speeds with H08Mn2Si low alloy carbon steel welding wire as wire. The effects of deposition speed on the macro size, microstructure and mechanical properties of stacking layer were investigated. The results show that with the deposition speed increasing, the surface formation quality of stacking layer became better, the interlayer lines became clearer, and the macro size decreased. At a relatively high deposition speed, the ferrite grains in the stacking layer were relatively small, the content of pearlite was relatively high, and the microstructure was relatively uniform. With the increase of deposition speed, the tensile strength of stacking layer in both vertical direction and horizontal direction increased, the elongation decreased slightly, and the average microhardness inside increased. The tensile fracture was fiber-like and had a lot of dimples, indicating that the ductile fracture occurred.