The invention discloses a vacuum collection device for a water sample in a groundwater seepage model. The device comprises a simulated monitoring well, a sampling needle and a vacuum sampling pipe, wherein the simulated monitoring well and the sampling needle are hermitically connected to a simulated water separation layer of the seepage model. When the vacuum collection device is specifically used, a sealing plug of a vacuum sampling pipe cover is pressed on a bottle plug puncture needle to generate negative pressure in the vacuum sampling pipe; under the action of the negative pressure, the water sample is sucked into the vacuum sampling pipe through a water sample collection pipe; and after the sample is obtained, the vacuum sampling pipe is unplugged, and the sealing plug is still closed, so that the water sample is sealed in the vacuum sampling pipe. The vacuum collection device for the water sample is simple in structure and convenient to operate, and has the advantages of few retained water samples and implementation of no solute volatilization and leakage under multiple collection times.