This study explores the failure modes of plastics products caused by the defects in mold structure, raw materials, or processing conditions during the tests with a method of the failure mode and effects analysis (FMEA) procedure. By evaluating the severity, the occurrence, and the detection of each failure mode, the risk priority numbers of failure modes are constructed. Then the ranks of all failure modes could be determined. And some preventive actions for decreasing the failure risks are suggested in this study.