A pump device, comprising: a casing, comprising a cavity; a motor portion, comprising a rotating shaft rotatable around a central axis of the motor portion; a pump portion, wherein the pump portion is arranged on an axial side of the motor portion and in contact with the rotating shaft, wherein the pump portion can be driven by the rotating shaft to rotate; the pump portion comprises a first pressure chamber and a second pressure chamber, the pressure that the first pressure chamber bears is greater than the pressure that the second pressure chamber bears; a first bearing, connected with the casing and sleeved on the rotating shaft, the first bearing being located between the motor portion and the pump portion; a first oil groove, arranged on a first end surface of the first bearing facing the pump portion, and communicating with the first pressure chamber; and a throttle groove, provided on the first end surface, and communicating the first oil groove with a gap between the first bearing and the rotating shaft, characterized in that the pump device further comprises a buffer chamber arranged on an end surface of the first bearing away from the pump portion 1, wherein the buffer chamber comprises: a first wall surface, wherein the first wall surface is a wall surface of the buffer chamber close to the rotating shaft; from an end of an opening of the buffer chamber to a bottom wall of the buffer chamber, a distance between the first wall surface and the rotating shaft increases 2, and the buffer chamber further comprises a second wall surface, wherein the second wall surface is arranged to face the first wall surface, from an end of the opening of the buffer chamber to the bottom wall of the buffer chamber, a distance between the second wall surface and the rotating shaft decreases 3. a casing, comprising a cavity; a motor portion, comprising a rotating shaft rotatable around a central axis of the motor portion; a pump portion, wherein the pump portion is arranged on an axial side of the motor portion and in contact with the rotating shaft, wherein the pump portion can be driven by the rotating shaft to rotate; the pump portion comprises a first pressure chamber and a second pressure chamber, the pressure that the first pressure chamber bears is greater than the pressure that the second pressure chamber bears; a first bearing, connected with the casing and sleeved on the rotating shaft, the first bearing being located between the motor portion and the pump portion; a first oil groove, arranged on a first end surface of the first bearing facing the pump portion, and communicating with the first pressure chamber; and a throttle groove, provided on the first end surface, and communicating the first oil groove with a gap between the first bearing and the rotating shaft, characterized in that the pump device further comprises a buffer chamber arranged on an end surface of the first bearing away from the pump portion 1, wherein the buffer chamber comprises: a first wall surface, wherein the first wall surface is a wall surface of the buffer chamber close to the rotating shaft; from an end of an opening of the buffer chamber to a bottom wall of the buffer chamber, a distance between the first wall surface and the rotating shaft increases 2, and the buffer chamber further comprises a second wall surface, wherein the second wall surface is arranged to face the first wall surface, from an end of the opening of the buffer chamber to the bottom wall of the buffer chamber, a distance between the second wall surface and the rotating shaft decreases 3. a first wall surface, wherein the first wall surface is a wall surface of the buffer chamber close to the rotating shaft; from an end of an opening of the buffer chamber to a bottom wall of the buffer chamber, a distance between the first wall surface and the rotating shaft increases 2, and the buffer chamber further comprises a second wall surface, wherein the second wall surface is arranged to face the first wall surface, from an end of the opening of the buffer chamber to the bottom wall of the buffer chamber, a distance between the second wall surface and the rotating shaft decreases 3.