Linearity,as an important index to evaluate the performance parameters of detectors,has a direct impact on the use of users.Two different evaluation schemes,which are linear fitting of full-band blackbody irradiation power and pixel response rate and linear fitting of wave-band irradiation power and output signal voltage,are analyzed and discussed using two band detectors as experimental devices.The results of linearity fitting of full-band blackbody irradiation power are poor,the non-linearity is about 6 %,and the non-linearity fitting with wave-band is within 0.5 %.So,it is determined that the linearity fitted by band irradiation power has higher accuracy,which provides a guidance basis for evaluating the performance of detector intuitively.