Semi-automatic ventilation device for greenhouse

The semi-automatic ventilation device comprises a ceiling frame, ventilation frames and an auxiliary air frame, the ceiling frame comprises a ceiling and a ventilation pipe, the ventilation pipe is installed in the middle of the ceiling and fixedly connected with the ceiling, the ventilation frames are symmetrically arranged at the two ends of the ventilation pipe and fixedly connected with the ceiling, and the auxiliary air frame is fixedly connected with the ceiling. The auxiliary air frames are installed on the two sides of the ceiling, the auxiliary air frames and the ceiling are fixedly connected, the ventilation pipe is installed in the middle of the ceiling frame, the two ends of the ventilation pipe can be conveniently ventilated with the outside, external air can be used for ventilation through strip-shaped grooves after entering the ventilation pipe, and meanwhile the auxiliary air frames are installed at the two ends of the ventilation pipe; it is guaranteed that a user can control the angle betwee