Abstract: A pot experiment of hot pepper was conducted at Agrometeorology Research Station of Jiangsu Province from April to July, 2015 to assess the effect of irrigation water salinity on evapotranspiration, yield, fruit quality and water use efficiency. Five salinity treatments of 0.9(CK), 1.6, 2.7, 4.7 and 7 dS/m were used and each treatment was replicated 4 times. The 20 pots were completely randomized block design. Irrigation water salinity was increasing by adding 1∶1 milli equivalent concentrations of NaCl and CaCl2 to half strength Hoagland solution. Plants were irrigated with 120% of evapotranspiration. A glass bottle was set underneath each pot to collect drainage water amount. Evapotranspiration was calculated by water balance method. Results showed that the soil salinity was accumulated when irrigated with increasing salinity content of irrigation water. The electrical conductivities of saturated soil extracts(EC_e) was significant(P<0.001) linearly increased with the increase of irrigation water salinity. Evapotranspiration significant linearly decreased with the irrigation water salinity and EC_e, and the effect was mainly on fruit maturation and harvesting stage. Compared to CK, the seasonal evapotranspiration was significantly decreased by 13%-40% except for irrigation water salinity of 1.6 dS/m. Compared with CK, the yield of hot pepper significantly decreased by 27%-65% when irrigation water salinity higher than 1.6 dS/m. This was as a result of reduction in single fruit weight and single fruit number. The relationship between relative yield and EC_e was analyzed. The percentage yield loss per unit increase in EC_e beyond the threshold value was 5.61% and threshold value of EC_e was 1.5 dS/m, which presented the hot pepper was considered moderately sensitive to salinity. The yield response factor was 1.72, indicating that hot pepper was sensitive to water stress caused by salinity. The fruit length, maximum fruit width, singe fruit weight and number and fruit water content decreased, while fruit firmness and total soluble solid increased as irrigation water salinity increased. The water use efficiency of hot pepper also significant linearly decreased with the irrigation water salinity. This was because salinity reduced water loss more than the reduced yield. When irrigation water salinity was 1.6 dS/m, the evapotranspiration, yield and water use efficiency of hot pepper was not significant decreased. Thus the irrigation water salinity of 1.6 dS/m could be adapted to irrigation when fresh water was limited. The study could provide valuable information for production of hot pepper and improving water use efficiency under saline irrigation.