In this paper, we introduce a novel Flip INvariant Descriptor (FIND). FIND improves the degenerated performance resulted from image flips and reduces both space and time costs. Flip invariance of FIND enables the intractable flip detection to be achieved easily, instead of duplicately implementing the procedure. To alleviate the pressure brought by the increasing scale of image and video data, FIND utilizes a concise structure with less storage space. Comparing to SIFT, FIND reduces 35.94% length for a descriptor. We compare FIND against SIFT with respect to accuracy, speed and space cost. An application to image search over a database of 3.27 million descriptors is also shown.