The invention is applicable to the technical field of electric power, and provides a cable trench draining control method and system. The method includes that an environment information collecting device collects the first environment information inside the cable trench and sends the first environment information beyond the first preset range to the corresponding information transfer node; the information transfer node acquires the second environment information sent by the environment information collecting device and encapsulates each piece of second environment information and the current time information one by one and sends the information to a server; the server monitors the real-time status of each cable trench according to the second environment information that exceeds the second preset range and generates a control command according to the monitoring result and sends the control command to a control device arranged in the corresponding drain trench; and the control device executes at least one of draining, dehumidifying and heating according to the control command. The method can monitor the state of the cable trench in real time, improve the monitoring efficiency and accuracy of the cable trench status, and meanwhile, realize the intelligent monitoring of the cable trench status.