The invention discloses an SDH-based system and method for remotely controlling the temperature in a transformer substation. The temperatures of different small rooms in the transformer substation are detected in real time through a temperature monitoring and acquisition module, an alarm is given when the limit is exceeded, air conditioners are remotely controlled, and thus the problem that the temperature in the transformer substation cannot be remotely monitored and controlled in the running and working process of devices is solved, the service life of primary devices and secondary devices is prolonged, the interruption time of a communication system of the transformer substation is substantially shortened, and a powerful guarantee is provided for normal operation of electrical production activities. The SDH-based system is high in temperature measuring precision, low in power consumption and high in stability, the environment temperature can be measured in real time, the air conditioners can be turned on or off remotely, the running modes of the air conditioners can be changed remotely, the functions of temperature regulation, air supply and the like are achieved remotely, and thus the temperature of a switch room and a machine room in the transformer substation can be regulated. Construction is easy and convenient to perform, popularization is facilitated, the running environment of the devices can be optimized, the fault rate of the devices can be reduced obviously, energy conservation and emission reduction are achieved, the working intensity of operation and maintenance personnel is reduced, and the device operation and management level of a company is improved.