Object detection in aerial images is a task of predicting the target categories while locating the objects. Since the different categories of objects may have similar shapes and textures in aerial images, we propose context-aware layer to provide global and robust features for classification and regression branch. In addition, we propose the CentraBox to reduce unnecessary training samples during the training phase. We also propose the instance-level normalization to balance the contributions among the instances. Finally, we compare our method with other methods in terms of accuracy, speed and parameters usage. Moreover, we also compare our own method with different hyper-parameter settings.