The invention provides a low-pulsation small-flow gas sucking pump. The low-pulsation small-flow gas sucking pump comprises a gas sucking pump body, wherein the gas sucking pump body is installed on a pump bracket, a gas containing cavity is formed in the pump bracket, the top of the gas containing cavity is provided with a gas containing cavity upper gas outlet and a gas containing cavity upper gas inlet, a gas containing cavity lower gas outlet and a gas containing cavity lower gas inlet which are isolated from each other are formed in the bottom of the gas containing cavity, the gas containing cavity lower gas outlet communicates with a gas inlet of the gas sucking pump body, the gas containing cavity lower gas inlet communicates with a gas outlet of the gas sucking pump body, the gas containing cavity upper gas outlet is connected to a flexible gas capacitor gas inlet formed in a flexible gas capacitor through a pipeline, and the flexible gas capacitor is provided with a flexible gas capacitor gas outlet communicating with the atmosphere and a pressure measuring port used for being connected to a micro differential pressure sensor. According to the low-pulsation small-flow gas sucking pump, the pulsation of the instantaneous flow is greatly reduced in the sucking flow range, and the calculation accuracy of the accumulated flow is improved. The lower limit of the sucking flow of the pump is stably started, and the lower limit and the range of the sucking flow can be adjusted according to requirements.