Abstract: In order to realize water-saving, high quality and high yield of hot pepper by scientifically and rationally regulating soil water, the influence of different irrigation patterns on chlorophyll fluorescence parameters of hot pepper under the condition of rain-shelter with OS5-FL modulated chlorophyll fluorometer was studied. The results showed that with the reduce of irrigation water volume, hot pepper variable fluorescence(Fv)、maximum fluorescence(Fm)、the ratio of the variable to maximum fluorescence(Fv/Fm), the ratio of the variable to minimal fluorescence(Fv/Fo) and the photochemical quenching coefficient(qP) and non-photochemical quenching coefficient(qN) at the four growing stage decreased, while the minimal fluorescence(Fo) raised. Analysis indicated that photosystem Ⅱ damaged, and primary light energy conversion of PSⅡ(Fv/Fm), potential activities of PSⅡ(Fv/Fo) decreased, photosynthetic electron transport, photosynthetic primary reaction inhibited, the ability of heat disseminate increased. In the three treatments of DI50, 1PRD and 2PRD. Chlorophyll fluorescence parameters of hot pepper under 1PRD changed smaller compared to CK. However, the chlorophyll fluorescence parameters were not significantly affected by irrigation patterns during four measurement.