Inland water is an important resource for human beings. Tiangong-2 Interferometric Imaging Radar Altimeter （TG2-InIRA） is the first spaceborne radar altimeter which adopts the short-baseline interferometry to measure the digital elevation model of oceans and inland waters on Earth with wide swath. It is also the first spaceborne imaging radar which takes an obviously small incidence to acquire the strong quasi-specular scattering of earth water. Nevertheless， the scattering of water is easily affected by observation angles and changes over time under different weather conditions， it is thus necessary to fuse the TG2-InIRA images of multi-angle and multi-temporal for a comprehensive sensing of the real state of inland water. Therefore， a Discrete Wavelet Transform （DWT）-based fusion of inland water images acquired by TG2-InIRA is proposed， where the DWT is used to decompose the to be fused source images into two components of low frequency and high frequency. Different fusion rules should be designed for these two components in view of the fact that the morphology of inland water shows great diversity in frequency domain. Specifically， a Canny operator-based fusion rule is proposed for the low-frequency components so as to highlight the global features of large water bodies such as rivers and lakes. A contrast enhancement-based fusion rule is developed for the high-frequency components so as to refine the local features such as small water bodies and water edges. Comparative experiments on two multi-angle and multi-temporal TG2-InIRA images in Anqing area with five widely-used fusion methods including the weighted averaging， the Laplace pyramid-based fusion， the non-subsampled contourlet transform-based fusion and two other DWT-based fusions demonstrate the obviously improved performance on quantitative indexes such as clarity， standard deviation， mean square error and cross-entropy. The image segmentation experiment based on the fused images further shows the nice fineness and integrity performance of the proposed approach on water body extraction.