The invention discloses a cable monitoring method and system. The method includes the steps: acquiring the temperature of a cable to be monitored by a sensor; transmitting the temperature of the cable to be monitored to a monitoring terminal by the sensor; calculating the needed adjustment quantity of the transmission capacity of the cable to be monitored according to a preset algorithm and the temperature by the monitoring terminal; adjusting the transmission capacity of the cable to be monitored according to the needed adjustment quantity by the monitoring terminal. By the aid of the technical scheme, the state of the cable is monitored, the transmission capacity of the cable is adjusted, so that the law of the insulation level of the cable can be dynamically analyzed, safety of the high-voltage cable is enhanced, and the method solves the technical problem that the high-voltage cable with high output capacity easily has accidents and is low in safety due to the fact that operation and maintenance basis cannot be provided in the prior art.