The invention provides an internal environment regulating and controlling system of a switch cabinet. The internal environment regulating and controlling system comprises a humidity detecting device, a temperature detecting device, a processing module, a ventilating device and a heating device. The temperature detecting device is used for outputting the value of the humidity in the switch cabinet. The temperature detecting device is used for outputting the value of the temperature in the switch cabinet. The processing module is used for comparing the humidity value with the preset upper humidity value limit, comparing the temperature value with the preset upper temperature value limit and comparing the temperature value with the preset lower temperature value limit. When the temperature value exceeds the upper temperature value limit or the humidity value exceeds the upper humidity value limit, a ventilation signal is output, and when the temperature value is lower than the lower temperature value limit, a heating signal is output. A ventilation module is used for ventilating the interior of the switch cabinet according to the ventilation signal. A heating module is used for heating the interior of the switch cabinet according to the heating signal. The temperature and the humidity in the switch cabinet can be adjusted to enable electrical devices in the switch cabinet to normally run, and condensation or corona discharge or electric breakdown or equipment oxidation or other accidents of the electrical devices can be avoided.