We propose DeepHuman, a deep learning based framework for 3D human reconstruction from a single RGB image. Since this problem is highly intractable, we adopt a stage-wise, coarse-to-fine method consisting of three steps, namely inner body estimation, outer surface reconstruction and frontal surface detail refinement. Once an inner body is estimated from the given image, our method generates a dense semantic representation from the inner body to encode body shape and pose and to bridge the 2D image plane and 3D space. An image-guided volume-to-volume translation CNN is introduced to reconstruct the outer surface given the input image and the dense semantic representation. One key feature of our network is that it fuses different scales of image features into the 3D space through volumetric feature transformation, which helps to recover details of the subject's outer surface geometry.