The invention relates to a thermistor-type infrared detector noise testing system and a testing method. In view of the structural characteristics of a manganese cobalt nickel oxide infrared detector,based on detailed analysis on a noise model, a design scheme for a noise testing method and a corresponding testing system under different bias voltage is designed. In comparison with the prior art, the system can accurately test the noise time domain signals and the frequency domain signals of the infrared detector, information such as band-frequency noise in a range, point-frequency noise, burstnoise amplitude and characteristic frequency are extracted, different bias voltage can be switched, test analysis on the noise under different bias voltage can be carried out, and through testing a noise coefficient under different bias voltage, a detector with a doubtful point can be eliminated in advance.