Interferometric Imaging Radar Altimeter (InIRA) on board Chinese TG-2 space laboratory is dedicated to enable a wide-swath measure of the sea surface height by interferometric processing synthetic aperture radar (SAR) images. In this paper, a simple fusion algorithm is developed for InIRA SAR image and GoogleEarth optical image based on hue-saturation-value (HSV) color model. While the H and S components of optical image are reserved for the fusion, the V component of the fusion image is a weighted linear combination of SAR image and the V component of optical image, with the image entropy as weight. Experimental results exhibit not only the nice performance of the fusion scheme but also the potential of InIRA in inland water observation.