The invention provides a method for in situ returning stumps of capsicum frutescens L. in a sunlight greenhouse to the field and application of the method. The method comprises the steps of: directlyperforming mechanic smashing on the stumps of capsicum frutescens L. in the sunlight greenhouse, covering soil with the smashed stumps, spraying water to the smashed stump sections of capsicum frutescens L., and then performing primary high-temperature degradation; applying organic fertilizer on the surface of the soil, performing rotary tillage and deep plowing on the soil which contains the smashed stump sections of capsicum frutescens L. and is obtained after organic fertilizer covering and primary high-temperature degradation are conducted, performing irrigation, covering the soil with mulching film, and then performing secondary high-temperature degradation so as to kill pathogenic bacteria and nematodes in a soil layer within 20-30 cm or above and decompose the smashed stump sectionsof capsicum frutescens L. in the soil, and then performing ventilation and air exchange; measuring and adjusting the pH value of the soil to 5.8-6.8; before final planting of the next crop of plantsis conducted, performing mobile steam disinfection on the soil so as to kill pathogenic bacteria and nematodes in a soil layer at 40 cm or above and loosen the soil. Through the method, the yield of capsicum frutescens L. can be increased significantly, and pests and diseases can be reduced.