Abstract: The optimal solution to the scheduling problem to reentrant medical devices testing process for the constraint conditions is studied. Firstly, a formal Petri Net（PN） model is built by analysis of scheduling constraints, optimization objectives, system stability and other system properties. Furthermore, based on the PN model and its scheduling constraints, a feasible scheduling solution is calculated. It combines with continuous recycling constraint of medical test and established time constraint matrix. The feasible solution is eventually optimized. Finally, the practical analysis of medical testing systems and CPN Tools simulation method turn out the result for the established models and methods are valid.