The automatic closing mercury pot for the manometer includes a pot body and a pot seat. The pot seat is equipped with an automatic switch to control the opening and closing of the mercury channel. The automatic switch can automatically open the mercury channel after the sphygmomanometer cover is opened, and automatically close the mercury channel after the sphygmomanometer cover is closed, so that the mercury leakage phenomenon caused by the user forgetting to close the switch can be avoided, so as to reduce waste and Environmental pollution, also won't be due to mercury leakage and wrong measurement of blood pressure, in line with the national measurement requirements.