Abstract: An oil separator of an outdoor unit of an air conditioner includes a tank body, an inlet pipe, a gas outlet pipe and a separating member, the lower end of the tank body being provided with an oil outlet, the inlet pipe being connected to the tank body, the central line of the inlet pipe being parallel to a horizontal direction, the gas outlet pipe being connected to the upper end of the tank body. A mixture has a tangential speed and rotates in the tank body, and oil-gas separation is realized by a centrifugal force, and kinetic energy loss is reduced. The inlet pipe is parallel to the horizontal direction so as to reduce unnecessary collisions between the mixture and the upper end of the tank body, and to allow sufficient time for the mixture to be separated.