Provided is a double-sided laser titanium-steel clad plate full penetration welding method based on transition layer control. The method is suitable for welding of titanium-steel clad plates. The double-sided laser titanium-steel clad plate full penetration welding method based on transition layer control is provided in order to solve the problems that in the existing titanium-steel clad plate welding process, operation is complex, accumulated heat input is large, welding stress deformation is large, and the welding efficiency is low. The method comprises following steps that 1, semi-elliptical groove is prepared along a titanium-steel clad plate interface; 2, a welding area is cleaned; 3, a transition layer is prepared, wherein the transition layer is prepared by mixing a certain proportion of metal powder to be uniform; 4, laser welding is conducted on both sides, wherein after assembling and clamping are conducted, the titanium-steel clad plate is preheated to 100 DEG C to 120 DEG C, synchronous welding is conducted on the two sides with laser, and when welding is conducted, metal on the two sides is merged uniformly by controlling the linear energy. According to the double-sided laser titanium-steel clad plate full penetration welding method based on transition layer control, by means of control of the transition layer, the mechanical property of a welded joint of the titanium-steel clad plate is improved, an existing welding technology is simplified, and high-quality and high-efficiency welding is achieved.