The invention discloses a fault detection method of a wireless sensor network and relates to the technical field of wireless sensor network. The fault detection method includes the following steps: S1 detecting actual measuring value of sensor nodes in real time and determining health level of the nodes according to the predefined health level standard; S2 updating reputation value of the nodes in real time according to the health level; S3 judging whether the nodes have fault or not according to the reputation value. The fault detection method is small in energy consumption and has high fault detection accuracy when used for detecting fault.