Accuracy of thermal control system plays a crucial role in space optical remote sensor imaging quality. To realize precise thermal control, first of all must have a high precision of temperature measurement circuit. In order to satisfy a space optical remote sensor thermal control system of high precision temperature measurement requirements, this paper choose NTC thermistor as the temperature measurement components, and designed a temperature acquisition circuit based on constant current source. Expounds the constantcurrent source temperature measurement circuit, analyzed the error of current source, instrument amplifier, the circuit voltage follower and AD converter. The experimental results show that the temperature detection circuit design of constant current source is stable and reliable, after calibration and compensation of temperature measuring circuit, temperature measurement precision is 0.025℃, satisfy the precision thermal control requirements of space optical remote sensor.