Several specific and feasible changing topology ways of variable topology parallel mechanism are given. The 4—TPT parallel mechanism is selected for further analysis on one of the changing topology ways and a large number of symmetrical or unsymmetrical variable topology structure parallel mechanisms are obtained, which verifies the validity of the process mentioned above. And also, the characteristics of this kind of variable topology structure parallel mechanisms are explored. The results show that workspace and dexterity of type variable topology structure parallel mechanism obtained are enhanced remarkably. 