The invention relates to a casting type bus bar fault point detection method. The method comprises the first step of measuring total ground insulation resistance values of all phases of an integral casting type bus bar and positioning a fault phase, the second step of selecting the casting type bus bar in a unit area of the integral casting type bus bar as a detected area, treating a surface material of the detected area through a conducting solution and grounding the detected area, the third step of measuring the total ground insulation resistance value of the fault phase of the integral casting type bus bar and judging whether fault points exist in the detected area, and the fourth step of judging whether the integral casting type bus bar is completely detected or not, if yes, ending the detection process, and if not, drying the casting type bus bar in the detected area and continuing to select the casting type bus bar in a next unit area as the detected area for detection. According to the method, the surface material of the casting type bus bar is treated through the conducting solution, for example in a water spraying manner to make the fault worse, so the fault points of the casting type bus bar can be effectively positioned on the condition of not damaging the casting type bus bar, and the time for finding the fault points is greatly shortened.