As an important component to suppress the operating overvoltage and inrush current of circuit breakers during the closing process, the pre-insertion resistor is widely used in the circuit breakers of 550 kV and above, but due to the harsh operating conditions, the probability of failure is relatively high. In order to fully grasp the abnormal causes of circuit breaker pre-insertion resistor fault and accurately formulate reliability control measures, the typical cases of abnormal failure of the pre-insertion resistor and its related components are comprehensively sorted out, five types of problems such as breakage of the resistor, internal foreign body discharge, poor assembly process, thermal breakdown and abnormal resistance value are summarized, and the causes of the problems are analyzed one by one. Further, based on the problem, the reliability improvement measures of circuit breaker with pre-insertion resistor are proposed from the aspects of structural design, test, production and transportation, operation and maintenance control, equipment selection and so on. The research has guiding significance to prevent the failure of closing resistance and ensure the safe and stable operation of power grid.