A fault detection method for a three-phase power distribution system, which includes three phase lines and a neutral line. The three phase lines intersect with the neutral line at a neutral point, the three phase lines include a first phase line, a second phase line, and a third phase line, and at least one of the three phase lines is connected to the neutral line. The method includes: obtaining a voltage between every two phase lines; obtaining a voltage between each phase line and the neutral point based on the voltage between every two phase lines; obtaining a voltage between the neutral line and the neutral point based on a voltage between each phase line and the neutral line and the voltage between each phase line and the neutral point; and detecting the voltage between the neutral line and the neutral point, whether a fault occurs in the neutral line.