Abstract: In view of the “qualified but non-enveloped” phenomenon in the test data of monopropellant thrusters, in order to better understand the product characteristics and to discover the product risk points in advance, this paper constructed the data envelope on the basis of focusing on six key characteristic parameters of monopropellant thrusters and by using the ground test data sets of the key characteristics of forty-seven successfully flown thrusters. The individual control chart algorithm was selected for the envelope analysis, and it was found that some characteristic parameters of the thruster appeared to be “qualified but non-enveloped”. Further inspection revealed that the performance of the thruster did not meet the delivery requirements. The above method is simple in calculation and convenient in operation, which may help to identify the weak links of products in the production process in advance, so that the corresponding risk analysis can be carried out as early as possible to improve the product reliability.