Abstract: Through field experiment，the water use efficiency of upland rice in different water treatments was studied．The results show that diurnal changes of photosynthesis rate，transpiration rate and the water use efficiency of“Upland rice 502”and“Jindao 305”are similar in elongation and flowering stage．Both photosynthesis rate and transpiration rate are higher in the middle of the day than any other times．The diurnal change of water use efficiency looks like a‘L’，The water use efficiency of“Upland rice 502”is higher than that of“Jindao 305”under enough irrigation and water deficit treatments．The water use efficiencies of agricultural water consumption of“Upland rice 502”and“Jindao 305”are lower than those of irrigation，especially water use efficiencies of the two varieties under water deficit condition are higher than those of under enough irrigation respectively， Water use efficiencies of agricultural water consumption and irrigation of “Jindao 305”are lower than those of“Upland rice 502”．