A digital video recorder with a fast-detaching hard disk assembly has case, an ejector frame and a hard disk. The case has an opening and cover corresponding to the opening. The ejector frame has a hard disk housing, two X-frames, and is raiseably mounted in the case corresponding to the opening. The hard disk is mounted on the hard disk housing. To remove the hard disk from the case, a person removes the cover and the hard disk housing will automatically raise through the opening for easy replacement, removal or maintenance access.