For real-time accurate target segmentation is a major factor restricting infrared radiation characteristic measuring real-time processing system, a real-time accurate segmentation method is proposed based on miss distance of target. Firstly, this article analyzes the characteristics of the target and common image segmentation algorithms. Then, choose One-dimensional Minimum Error method (OME) and Two-dimensional Minimum Error method (TME) as the main study object for their suitable target characteristics and good segmentation results. Finally, propose using the miss distance to reduce gray level and processing area after analyzing the bottleneck of OME and TME, realized real-time accurate segmentation. Simulation results show that a frame processing time is less than 10 ms, which can meet the requirements of the infrared radiation characteristic measuring real-time processing.