The invention relates to a semiconductor refrigerator closed-loop control method applied to a space environment and belongs to the spaceflight optical remote sensor technical field. The method includes the following steps that: a bridge type series circuit is adopted to acquire the current temperature V1 of the focal plane of a detector; the difference of a characterization parameter V1 of the current temperature of the focal plane of the detector and a characterization parameter V2 of the target temperature of the focal plane of the detector is obtained and amplified through an operational amplifier, and then is transmitted to a PID control circuit, so that control voltage can be obtained; and the control voltage outputted by the PID control circuit is transmitted to a driving circuit, and the driving circuit controls current passing through a semiconductor refrigerator, so that refrigeration can be performed for the focal plane of the detector. According to the closed-loop control circuit adopted by the method of the invention, bridge type series resistors are adopted to measure the temperature of the focal plane of the detector; at a temperature control point, the reaction of divided voltage to variation of the resistance value of a thermistor caused by temperature is most sensitive, wherein the resistance value at the temperature control point is selected, and therefore, measurement errors can be decreased, and high-precision measurement can be realized, and thus, high-precision control can be realized.