Abstract: A microcuvette is provided, including a body having a slit inside. The slit connects to an entry slit and an exit slit, and the entry slit and the exit slit are on the opposite side of the body. The microcuvette is characterized in that the slit includes a drainage slit, an optical measuring slit, and a protecting slit. The drainage slit directly connects to the entry slit, the optical measuring slit, and the protecting slit. The protecting slit at least partially surrounds the optical measuring slit and connects to the exit slit. The drainage slit has an average width not larger than the optical measuring slit, and the protecting slit has a width larger than the optical measuring slit. The microcuvette of the present invention is convenient to use, disposable, and can reduce factors affecting measurement results.