The invention relates to the technical field of breast pumping articles, and particularly relates to a breast pump. The breast pump comprises a breast milk collector, a pumping source and a breast milk pumping shield, wherein the pumping source is provided with a relief port and an air suction port; the breast milk pumping shield is provided with a relief passageway and a breast milk outlet; the breast milk outlet is communicated with the breast milk collector through a first hose; the breast milk collector is communicated with the air suction port of the pumping source through a second hose; the relief passageway is communicated with the relief port of the pumping source through a third hose; when the breast pump is used, the breast milk pumping shield covers the breasts and does not need to be held by hands as the breast milk pumping shield is separated from the breast milk collector; the pumping source is started for pumping, and air pressure in the breast milk collector and the breast pumping shield turns to be negative pressure; and when the air pressure is lower than the pressure in the breasts, breast milk is pumped out from the nippers into the breast milk pumping shield, and then the pumping source relieves, the pressure in the breast milk pumping shield is increased instantly after relief, the pressure of the breast milk collector is still in the negative pressure state, and the breast milk rapidly flows to the breast milk collector from the breast milk pumping shield through the first hose under the function of the pressure difference, so as to achieve the effect that no residual breast milk is left.