Abstract: A method and device for 3D object detection. The method comprises the steps of: generating one or more fused images(201) based on a pair of images(530), the pair of images (530) including a left view image(101,710a) and a right view image(102,710b); extracting one or more fused features from the fused images(201) by a single backbone network(210) of a share network with feature unmixing (SNFU,540); unmixing the fused features to a left view-aware feature and a right view-aware feature by a feature unmixing sub-network(220) of the SNFU(540); predicting the 3D object based on the left view-aware feature and the right view-aware feature; and determining spatial features of the predicted 3D object. The proposed method and device can reduce the computation complexity to the level of that in monocular based 2D object detection so as to improve the computation efficiency while keeping high precision.