Abstract: Abstract: Transpiration models are important for determining crop water demand and irrigation amount. In this study, a simple transpiration model was proposed by investigating the relationship between daily transpiration and its influencing factors and the model was tested by experimental values and used for study the influence of irrigation determined by the model on growth, yield and quality of muskmelon. The experiment was carried out in greenhouse located in Yangling, Shannxi. In 2015, the irrigation was based on the measured transpiration. The leaf area index, temperature, relative humidity and photosynthetically active radiation were measured. Their relationships with transpiration were studied. Based on the relationships, the model was established. In 2016, 4 irrigation levels (80%ET, 100%ET, 120%ET and 140%ET) were designed. The results of the irrigation level of 100%ET were used for model validation. Then the fruit biomass, yield and quality were determined. The results showed that the effect of influencing factors on the transpiration was ordered by leaf area index > daily average temperature > daily average relative humidity > intensity of solar radiation. A model was built for transpiration simulation. The determination coefficient was 0.984. The validation of model showed that the root mean square error was 41.83 g, the relative error was 11.4% and the determination coefficient was 0.937. It suggested that the model could well fit the transpiration. The irrigation experiment based on the proposed model showed that the different levels of irrigation had significant effects on dry matter accumulation and distribution. From stretching stage to fruiting stage, dry matter accumulation in different treatments was highest in the 120%ET and 140ET and lowest in the 80%ET. The dry matter accumulation of fruit in fruiting stage was the highest in the 120%ET and the lowest in the 80%ET. The dry matter distribution in the stretching stage showed leaf > stem > root, the dry matter distribution in flowering stage showed that leaf > fruit > stem > root, and the dry matter distribution in fruiting stage showed that fruit > leaf > stem > root. The yield of muskmelon declined in the low or high level of irrigation based on transpiration model and the yield of 120%ET was the highest with 1.23 kg/plant. The water use efficiency of muskmelon increased with decreasing irrigation level. The content of soluble solid, soluble protein and soluble sugar showed a rising then declined trend with the irrigation levels. The subordinate function value of fruit quality was 4.69 (120%ET) > 3.45 (100%ET) > 3.34 (80%ET) > 2.27 (140%ET). Thus, the treatment of 120%ET was the best for muskmelon growth, quality and yield.