Zhan’s five wheels sand clock was a significant design of time-keeping device in China during the 14th century. With a sand wheel as the power source and four pairs of gears as the transmission system, it was able to indicate time by its hand on the clock dial. Although this invention is not preserved, an ancient literature provides a clear record of its mechanical structure of gear transmission with engineering data. This paper introduces the background of Zhan’s sand clock and presents a translation version of those descriptions of this device. Moreover, a mechanical analysis is made based on the engineering data provided in the original literature, and all relevant factors and mechanical design parameters about its power source are listed and discussed. Finally, the feasibility of Zhan’s sand clock is verified through a reconstruction design and prototype testing.