Abstract: Described here in the paper is the method for reinforcement of opening of the drawn tee and pipeline.Anal- yzed is the mathematic model for the said reinforcement.This model is used for relevant calculation.Based on the analysis result,it is identified that under given site-required conditions(i.e.the designed pressure,main ODand branch OD of the tee,and the steel grade),it is possible to use the said model to quickly calculate the designed wall thickness of the tee product,and moreover,with given designed wall thickness,it is also possible to reverse out the test pressure of the tee product by means of substituting the known parameters into the mathematic model.