Abstract: 【Objective】 To study the effects of water and fertilizer coupling on photosynthetic fluorescence, yield and quality of cucumber. 【Methods】 Taking "Xintaimici " cucumber as the test material, under the cultivation mode of yellow sand and slag composite substrate, four variables including irrigation amount, nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer were set up, and one half of the four variable quadratic general rotation combination design was used. 【Results】 (1) The net photosynthetic rate of cucumber increased with the increase of irrigation amount; under the condition of less water, proper fertilizer supply could improve the photosynthetic capacity of cucumber. (2) Under the water and nitrogen supply of 105% Ep, the lower P and K fertilizer was helpful to the chlorophyll synthesis of cucumber. Under 90% Ep water supply, the chloroplast pigment content of cucumber leaves was at a high level, and the maximum light conversion efficiency F_v / F_m was the highest. (3) Under the water supply of 75% Ep, higher N and K fertilizer, and lower P fertilizer could improve the single fruit weight of cucumber, and proper reduction of irrigation could improve the yield and quality of cucumber. 【Conclusion】 Under the cultivation mode of yellow sand and slag composite substrate, the optimal ratio of water and fertilizer for greenhouse cucumber production is C₁₆, that is 90% Ep and N 540 kg / hm²+ P₂O₅270 kg / hm² + K₂O 1,043 kg / hm².