Abstract:The diurnal variation characteristics of net photosynthesis rate and transpiration rate of 4 species of turfgrass with different water supply treats in sunny days were studied. The results show that the net photosynthesis rate diurnal variation curves of kentucky bluegrass and japanese lawngrass were double-peaked, while the curve of tall fescue and creeping bentgrass were three-peaked. The discrepancy of net photosynthesis rate among kentucky bluegrass, tall fescue, and creeping bentgrass with different water supply treats was extremely notable, while the variation of net photosynthesis among japanese lawngrass with different water supply treats was slight. The transpiration rate diurnal variation curves of 4 species of turfgrass were all double-peaked. The discrepancy of transpiration rate between kentucky bluegrass and tall fescue with different water supply treats was conspicuously notable. The transpiration rate of creeping bentgrass with different water supplies varied, but that of japanese lawngrass watered variably corresponded to each other. Optimal amount of watering of kentucky bluegrass and tall fescue was (70%～55%)W,while that of japanese lawngrass and of creeping bentgrass was (55%～40%)W.