Thermistor type infrared detector is the key element of the infrared earth sensor, which plays an important role in measuring precision of satellite attitude． The manufacturing process of the thermistor type infrared detector is complex, and the technical difficulties are great. Owing to the failure of these devices is mainly caused by noise, it is necessary to study new noise testing method to eliminate the failure devices. According to the structural characteristics of infrared detector based on thermistor of ternary Mn-Ni-Co oxide, the noise models were discussed in detail, and the noise test method based on infrared detector in different bias voltage was studied, then the corresponding testing system was designed. Test results show that the local noise and test accuracy of the system meet the requirements. The system will provide an experimental platform for the research of noise screening in different bias voltages, and lay a foundation for further analysis and research on the mechanism of noise variation in different bias voltages.