The invention discloses an intelligent comprehensive substation cable trench monitoring and protecting system which comprises a monitoring workstation, a cable trench workstation and a plurality of distributed modules, wherein each distributed module is used for acquiring a state signal of a trench cable; the state signal is input to the cable trench workstation for processing, and the cable trench workstation processes an input signal and transmits the processed signal to the monitoring workstation. The cable trench workstation and the distributed modules are connected to a cable trench environment, and the monitoring workstation enters a monitoring work room. The wireless data communication is stable and smooth, the monitoring workstation can remotely and timely master temperature change conditions of each temperature monitoring point in the cable trench, data are automatically acquired, and the monitoring labor intensity is lightened; and moreover, a water level signal in the environment in which the trench cables are positioned is acquired by employing a water level sensor, and the water level change can be timely and accurately reflected. A smoke signal in the environment in which the trench cables are positioned is acquired by employing a smoke sensor, an alarm signal is timely output, and the intelligent monitoring and protecting can be realized.