Abstract: Objective Welding positioner is the core component of a welding system. In order to obtain practical experience design theory and accurate structure selection, design calculation and structure of L-type welding positioner with single holding and double axis were studied in this paper. Methods Based on theoretical calculation and combined with experience data used in the factory, several key parameters in structural design of L-type welding positioner with single holding and double axis were analyzed and checked, and its main structure was studied. Results Taking typical non-standard L-type welding positioner with single holding and double axis as examples, based on theoretical calculation and practical verification, its basic mechanism was summarized, several key design parameters such as torque, moment of inertia and inertia torque related to load rate were analyzed and calculated in detail, and points for attention and relevant experience values were given. In addition, according to load condition, structure of light welding positioner and heavy welding positioner were studied respectively, and the corresponding structure types under different working conditions were given. Conclusion A set of effective design and calculation theoretical data of L-type welding positioner with single holding and double axis were obtained.