Abstract: A screening machine for superfine powder. The screening machine includes a casing, a screen drum, a funnel, a negative pressure chamber, a rotary air spray pipe, a drive motor, a blast pipe, and a feed pipe. The screen drum is disposed in the middle part of the inner cavity of the casing. The funnel is disposed beneath the casing. The opening of the screen drum is arranged on the bottom of the screen drum and communicates with the upper opening of the funnel. The inner cavity of the casing communicates with the external induced draft fan via the negative pressure chamber disposed on the upper part of the casing. The rotary air spray pipe is arranged in the space between the screen drum and the casing. The middle part of the transverse pipe is connected via a transmission with the drive motor.