A liquid pump (100) includes a top cover (40), a back plate (50), and a spacing member (60). The spacing member is sandwiched between the top cover and the back plate, thereby dividing an interior of the liquid pump into a fluid chamber (14) and a receiving cavity (16) isolated and hermetical from the fluid chamber. The fluid chamber is disposed between the top cover and the spacing member for receiving therein a fluid dynamic bearing (70) and a rotor (20) which drives working fluid to enter and leave the liquid pump. The receiving cavity is disposed between the spacing member and the back plate for receiving therein a stator (30) which drives the rotor to rotate in respective to the bearing.