The support chassis of large drilling equipment， serving as the support platform， is commonly assembled by welding numerous steel plates together. The residual stresses and deformations caused by welding have a certain impact on the strength and stiffness of the chassis. In this study， the finite element analysis method is applied. A finite element model is established for a representative T-type welded joint in the large support chassis， using a Gaussian moving heat source. Four different welding sequences and welding speeds are adopted to analyze their effects on welding stresses and deformations. Optimized welding sequences and welding speeds are obtained. Based on this， an overall welding scheme for the chassis is optimized. A comparative analysis is conducted on the welding stresses and deformations before and after optimization. The results show that the residual stress is reduced by approximately 7% and the maximum deformation is reduced by approximately 26% after optimization. The research results can provide reference for the formulation of welding processes.