Vegetable greenhouse capable of collecting rainwater for irrigation and use method thereof

According to the technical scheme, the vegetable greenhouse comprises a greenhouse body, a collecting mechanism is arranged at the top of the greenhouse body, a motor is arranged in the greenhouse body, the collecting mechanism comprises a transmission shaft, the transmission shaft is fixedly connected with the output end of the motor, and the top end of the transmission shaft extends to the outer side of the top of the greenhouse body; a sliding block is arranged at the top of the greenhouse body and arranged on the outer side of the transmission shaft in a sleeving mode, connecting plates are fixedly connected to the two sides of the sliding block, lifting rings are fixedly connected to the outer ends of the two connecting plates, two drainage pipes are fixedly embedded in the top of the greenhouse body, and water inlet pipes are fixedly connected to the tops of the two drainage pipes; the two lifting rings are arranged on the outer sides of the two water inlet pipes in a sleeving mode correspondingly, and