In the process of intelligent munitions attacking military objects, fast and accurate object detection is the key to the success of combat missions. There is a contradiction between the requirement of fast detection and the limitation of power consumption in deploying object detection algorithms on intelligent munitions. To meet the operational requirements of high altitude intelligent missile, the HiSilicon Hi3559AV100 chip with low power consumption and small volume is used as the carrier. By pruning the model and optimizing the small object detection strategy in large images, the detection accuracy of small objects in large images is improved by 30 %, and the real-time detection speed fps is increased by about 10 frames.