Farmland irrigation system

The utility model discloses a farmland irrigation system which comprises a main pipeline located above a vegetable bed and a spray head arranged on the main pipeline, the number of the main pipeline is one, sliding frames are arranged on the two sides of the vegetable bed, and the two ends of the main pipeline are arranged on the two sliding frames in a sliding mode respectively. A driving mechanism used for driving the main pipeline to slide on the sliding frame is arranged on one side of the sliding frame and comprises a supporting seat fixed to the ground, two rotating seats are installed on the supporting seat, rotating shafts are rotationally arranged on the rotating seats, chain wheels are installed on the rotating shafts, and chains are installed on the two chain wheels. A shifting rod is fixed to one chain link of the chain, a shifting plate is fixedly connected to the main pipeline, a kidney-shaped hole is formed in the shifting plate, and the shifting rod penetrates through the kidney-shaped hole an