A lightweight and efficient aerial image detection algorithm called Functional ShuffleNet YOLO (FS-YOLO) was proposed based on YOLOv8s, in order to address the issues of low detection accuracy for small targets and a large number of model parameters in current unmanned aerial vehicle (UAV) aerial image detection. A lightweight feature extraction network was introduced by reducing channel dimensions and improving the network architecture. This facilitated the efficient reuse of redundant feature information, generating more feature maps with fewer parameters, enhancing the model’s ability to extract and express feature information while significantly reducing the model size. Additionally, a content-aware feature recombination module was introduced during the feature fusion stage to enhance the attention on salient semantic information of small targets, thereby improving the detection performance of the network for aerial images. Experimental validation was conducted using the VisDrone dataset, and the results indicated that the proposed algorithm achieved a detection accuracy of 47.0% mAP0.5 with only 5.48 million parameters. This represented a 50.7% reduction in parameter count compared to the YOLOv8s benchmark algorithm, along with a 6.1% improvement in accuracy. Experimental results of DIOR dataset showed that FS-YOLO had strong generalization and was more competitive than other state-of-the-art algorithms.