The uncooled microbolometer has a severe temperature requirement for non-uniformity correction. An improved two-point non-uniformity correction method is proposed, which can operate in wider uniform substrate temperatures. This method can control the bias voltage of MOS transistors by memory and DAC to meet two restrictions about responsivity and offset before traditional two-point calibration is implemented. The simulation results seem that this non-uniformity correction can work at uniform substrate temperature with fluctuant range of 4K. The uncooled microbolometer has a severe temperature requirement for non-uniformity correction. The method can control the bias voltage of MOS transistors by memory and DAC To meet two restrictions about responsivity and offset before traditional two-point calibration is implemented. The simulation results seem that that non-uniformity correction can work at uniform substrate temperature with fluctuation range of 4K.