An improved structure of SL type static mixer was presented in this paper. The internal structure was described and two-phase flow field was analyzed. The comprehensive influencing factors were considered during analyzing the relationship of two-phase flowage parameters in practical device, and the theoretical study was carried out. The two-phase flow was impinged, separated, flowed around and merged by the two-phase flow. The mixture effect was strengthened. The analytic calculation was carried out according to the practicable turbulent flow pattern. The results are useful for the structure parameters effectively selection and the characteristic optimization for the improved structure of SL type static mixer.