Abstract: The temperature field of the twin-wire submerged arc welding was analyzed by finite element software ANSYS of secondary development.The calculation and loading of heat of mobile heat source were programmed by ANSYS parametric design language.In particular,by the use of vector,the calculation and loading operation were simplified and the efficiency of simulation was improved.The experiments verify that the algorithm of heat load makes simulation time and calculation reduce,and the algorithm is feasible and efficient.This algorithm can be applied to the thermal calculation and loading of temperature field for multiple wire welding.