Ship target detection is increasingly important to the current war today. Space-based Detection is an important way for getting the remote-sensing image included the ship target. Ship target characteristics analysis is the key of infrared image reorganization. It includes the thermal radiation of the target and background, Atmospheric transmission characteristics, imaging characteristics of detector and target characteristics. In order to get the simulation image in the infrared long-waveband, it analyses the characteristics of the infrared ship target and background. The target characteristics are known clearly, it could make the extraction process of target more effective and accurate. The target characteristics analysis is more conducive to the detection and recognition of the target.