As new generation of low alloy high strength steel, WELDOX960 is extensively applied into heavy-duty fields including engineering machine etc. This paper adopts mixed gas protection welding to make multi-layer and multi-channel welding to low alloy high strength steel WELDOX960, using match methods with different intensities to prepare six groups of samples, respectively. The performances including joint tension and impact etc are tested for analysis after welding. The result shows that backing welding is the most important technique process in multi-layer and multi-channel welding, which has significant impact to joint performance, in the precondition that the strength is satisfied, if the material with lower strength is taken as backing layer, toughness and plasticity of the joint can be improved significantly. For example, tensile strength of sample 50-90 reaches 966.3Mpa, which is the same as 90-90, however, its toughness increases by 15%.