Abstract: The diurnal and seasonal variations of photosynthetic active radiation (PAR) in the three seasons (hot-dry season,rainy season and foggy-cool season) were observed in a monoculture tea plantation and three different tree and tea mixed plantations (Chinese eaglewood-tea,camphor tree-tea,Flemingia macrophylla-tea) in Xishuangbanna.The results showed obvious seasonal variations in 4 plantations.The lower PAR appeared in the foggy-cool seasons,of which the lowest value was in the camphor tree-tea.As a whole,PAR was higher in hot-dry seasons.The diurnal accumulation of PAR was highest in the Flemingia macrophylla-tea pattern,and relatively low in the camphor tree-tea pattern.In hot-dry seasons,the diurnal accumulation of PAR was highest in monoculture tea plantation (38.57 mol·m-2·d-1).In foggy-cool seasons,however,the diurnal accumulation of PAR was lowest in Flemingia macrophylla-tea pattern (23.03 mol·m-2·d-1).The PAR ratio in camphor tree-tea plantation was 65.9 %,76.0% and 87.2 % to that of the monoculture tea plantation in hot-dry seasons,rainy seasons and foggy-cool seasons respectively,which had the lowest value to all other patterns.However,comparing to the monoculture tea plantation,the PAR ratios of Flemingiamacrophylla-tea pattern were 90.2 %,91.2 % and 99.9% to that of the monoculture tea plantation in hot-dry seasons,rainy seasons and foggy-cool seasons respectively,which was the highest of all patterns.PAR ratios were ranked as hot-dry season＜rainy season＜foggy-cool season by all the patterns.