Abstract: Computing dissipative welding material dosage is an important content of welding procedure.The parameter model of normal groove type is unified by modifying parameters on basic of describing both-side double-U-groove parameters, which is easy to compute cross-section area of weld.By decomposing the crosssection of weld on the model, calculating complex area is predigested to computing area of some simple graphs.For getting dosage of welding material from each welding procedure, the cross-section area of corresponding welding layer should be obtained.An idea and theory of calculating welding layer cross-section on welding layer thickness are presented.The arithmetic of layered iterative calculation is designed and is realized in the software, which the usage of calculating tool is explained.By calculating material from a real groove, the result shows that precision and efficiency of computing dissipative welding material are enhanced obviously.