Based on statistical feature of image blocks, a method for infrared object extraction is proposed. Firstly, the entire image is divided into blocks with scale decreasing gradually. According to the maximal value of the functions composed of statistical feature, seed region of the object and confined region that contains the entire object are obtained. Within the confined region, a fast method of region growing is applied to the seed region, and infrared object is extracted finally. Infrared aircraft images of varying object size are experimented to demonstrate the effectiveness of the proposed algorithm. Consuming time is also estimated if the proposed algorithm is implemented on the digital signal processor TMS320VC33-150, and it meets the requirement for real-time object extraction