Disclosed is a drip irrigation planting method for crop rotation of arch-shed onions and cantaloupes in an open field. According to the method, in the open field, arch-shed planting of the onions is conducted in spring, and direct-sowing planting of the cantaloupes is conducted in autumn. By means of the method, the planting structure can be adjusted, crop rotation within one year is achieved, the soil structure is improved, the occurrence of the continuous cropping obstacles of the cantaloupes is prevented, the use of pesticide, fertilizer and irrigation water is reduced, the production cost is reduced, and the quality of the cantaloupes is improved; through crop rotation, two-season cultivation within one year is achieved; compared with the modes of intercropping of cotton and cantaloupes, planting of cantaloupes in spring and autumn and crop-rotation furrow (flooding) irrigation planting of cantaloupes and sorghum, the economic benefits are high, the incidence rate of diseases and pests is low, the land utilization rate is high, the technology is easy to popularize, and the ecological benefits are obvious.