The present disclosure provides a method and an apparatus for detecting a 3D image, an electronic device, and a computer-readable medium. The method for detecting a 3D image includes layering a 3D image to obtain at least one 3D subimage. The 3D subimage contains a plurality of 2D images. The method includes performing an intra-layer clustering on the 3D subimage to obtain a superpixel grid. The method includes inputting the superpixel grid into a neural network for detecting. The method includes detecting, in response to detecting an object in the superpixel grid, the 3D subimage forming the superpixel grid containing the object to obtain and output a detection result.