The utility model relates to a safety detection system of an earthed wire. The safety detection system of the earthed wire comprises a vibration sensor, an environment monitor, a data processor and a monitoring terminal, wherein the vibration sensor is used for monitoring the vibration strength of the earthed wire; the environment monitor is used for monitoring ambient temperature, humidity, wind speed, wind direction and sunlight intensity of the earthed wire; the data processor is respectively in communication connection with the vibration sensor and the environment monitor and is used for fusing monitoring data received from the vibration sensor and the environment monitor; the monitoring terminal is in communication connection with the data processor, and is used for judging the fatigue strength of the earthed wire according to the processing data received by the data processor and sending alarm information according to the fatigue strength of the earthed wire. By virtue of the system, the fatigue strength of the earthed wire is accurately discovered in time; the earthed wire can be effectively maintained before disconnecting, so that the safe operation of the earthed wire can be guaranteed.