Model processing was one of the key factors affecting the forming accuracy of 3D printed titanium alloy parts. Several TC4 titanium alloy parts of typical shapes were printed by electron beam 3D printing as the research objectives. Through the precision detection of the 3D printed parts,the sources of errors caused by the model processing were analyzed,and several improvement measures were proposed. For example,by increasing the accuracy of the model to 0. 02 mm,the forming accuracy of the cylindrical part can be effectively improved. And for the lattice part,improving the accuracy of the STL data and optimizing the slice algorithm,maintaining the original shape of the slice before and after the slice is the way to increase the accuracy; for the thin cylindrical struts,the same struts are placed in the same direction,which can reduce the random effect of the placement angle on the deviation; for the irregular parts,the layout should be rationally arranged and the support should be reduced on the premise of satisfying the forming precision; for the thin-walled parts,the dimensional accuracy of its dangling zone can be increased by introducing more supporters.