The invention discloses a timing device comprising liquid used for indication, and a liquid cavity which is used for holding the liquid and is provided with a transparent closed window. The liquid cavity comprises a first chamber and a second chamber which communicate with each other, and the first chamber is arranged on the second chamber. A first channel allowing the liquid to pass fast, and a second channel allowing the liquid to pass slowly are arranged between the chambers. The first chamber further comprises a cache cavity. The positions of the cache cavity and the first channel are staggered. According to the timing device, the liquid cavity is divided, gravity is directly used for driving the liquid, the timing function of the timing device can be achieved, the structure is simple, and production cost is low. Meanwhile, through the combination of the design of a packaging bottle cap, a user can directly start the timing device while opening the cap, operation is simple, and popularization is easy.