Precision casting on the casting defects analysis and research, is one of the key technology to improve casting yield.However, the difficulty is not small.Mainly displays in:1, involves broad scope, such as alloy, casting, molding materials, casting equipment and production process of testing, etc.2, the diversity of the reasons for the casting defects, a kind of defects can be caused by a variety of reasons, and a kind of reason may cause several kinds of defects.3, the conditionality of technical measures such as using a certain measures, can prevent a particular type of defect, but it may lead to another kind of defect.4, influencing factors is difficult to control, such as quality of raw materials, such as the air temperature and humidity.