An improved model based on you only look once version 8 (YOLOv8) is proposed to solve the problem of low detection accuracy due to the diversity of object sizes in optical remote sensing images. Firstly, the feature pyramid network (FPN) structure of the original YOLOv8 mode is replaced by the generalized-FPN (GFPN) structure in GiraffeDet to realize the "cross-layer" and "cross-scale" adaptive feature fusion, to enrich the semantic information and spatial information on the feature map to improve the target detection ability of the model. Secondly, a pyramid-pool module of multi atrous spatial pyramid pooling (MASPP) is designed by using the idea of atrous convolution and feature pyramid structure to extract multi-scale features, so as to improve the processing ability of the model for multi-scale objects. The experimental results show that the detection accuracy of the improved YOLOv8 model on DIOR dataset is 92% and mean average precision (mAP) is 87.9%, respectively 3.5% and 1.7% higher than those of the original model. It is proved the detection and classification ability of the proposed model on multi-dimensional optical remote sensing target has been improved.