OBJECTIVE： To provide new idea and method for the prevention and control of drug quality risk in pharmaceutical enterprises in China. METHODS： Taking the deviation investigation of pyrogen test for a TCM injection produced by a pharmaceutical enterprise in Apr. 2014 as an example. Influential factors （including staff， machine， material， method， environment） which could induce the deviation were analyzed by Fault tree analysis （FTA） method and Failure mode， effects and criticality analysis （FMECA） method. Both systematic drug quality deviation investigation and risk assessment model were established. RESULTS & CONCLUSIONS： The direct reason for deviation of pyrogen test is that the experimental interval does not conform to requirements； root reason is that cost saving of laboratory leads to insufficient quantity of rabbits （i.e. there are loopholes in the management system of material element）. In addition， it is found that preparation and injection process of test solution lack of check and have poor traceability； preparation process has pyrogen and concentration error risk， and injection process has operating errors risk （i.e. there are loopholes in the element management system）. By revising Laboratory Animal Purchase and Management System， strengthening training and improving monitoring mechanism， adding recheck and video monitoring for preparation and injection steps of test solution by two persons， revising related documents and records， and other measures， this kind of deviation，which are caused by material not meeting the requirements， are effectively prevented from happening again. And，such deviations， which are caused by absence of recheck and other necessary operations in the process of inspection， are also effectively prevented from happening again. FMECA and FTA can effectively enhance the directionality of deviation investigation so as to improve the systematic and scientific property of investigation process. This mode has practical value.