Abstract: A double-model control theory of fuzzy-proportional is introduced,and its application in the seam tracking for the wheel robot with arc sens on is presented in detail,the particular process of design for this controller is given.For the integration of two unattached system,the toal control is difficult.A simple but useful compromise control tactic is adopted and flexible cooperation problem is settled well,it has proved by experiment that control characters are good and this controller can satisfy the requirements of welding application.