Thermal time constant is a key parameter of the microbolometer, which constrains the maximum frame frequency of uncooled infrared detector. The pixel-level test of thermal response time can truly reflect the physical thermal response time of the sensor, and provide timely and effective data support for product design optimization. It is very important to accurately measure this parameter. However, the current pixel-level test methods have not been able to effectively compensate the self-heating effect of microbolometers, and can not accurately measure the thermal response time. The effective thermal response time of the microbolometer is measured based on the frequency response method. The self-heating effect is compensated by the resistance temperature coefficient, and the physical thermal response time can be accurately measured. The physical thermal response time measured under different bias currents is experimentally analyzed. The results show that this method has high accuracy and strong stability.