To solve the problem of detecting salient moving object in the video shot by static camera, a new spatio-temporal object detection algorithm is proposed in this paper. Firstly, Hypercomplex Fourier Transform(HFT) is used to the current video frame to achieve the static salient region; then, the moving salient region is detected by an improved three frames difference algorithm; finally, the static salient region and the moving salient region are combined with dynamic fusion strategy. Compared with the traditional techniques, the proposed method is in better correspondence with the response of the human visual system and more suitable for salient moving object detection. The experimental results demonstrate the effectiveness of the proposed object detection method.