Abstract: 【Objective】 To discuss the effects of harvest maturity on browning and related metabolic enzymes of green walnut fruits in the hope of revealing the browning mechanism of it.The result provides suitable harvest period and a theoretical basis of the directional control of browning of green walnut fruits in production. 【Methods】 The 'Wen 185' green walnut fruits were studied as the test material, which were harvested respectively on August 22 (maturity Ⅰ, 125 d after flowering), August 27 (maturity Ⅱ, 130 d after flowering), and September 1 ( Maturity III, 135 d after flowering), and stored at (-1±1) ℃ and a relative humidity of 75%- 85%, and afterwards the browning index, total phenolic content and the metabolism-related enzymes of green walnut fruits were determined regularly. 【Results】 If the fruit skin maturity was different, its browning index was different. The browning index of maturity II (August 27th) was significantly lower than the other two maturity levels, and the total phenols and PPO, POD, PAL, SOD, CAT and APX activities were significantly higher than those of the other twos. The correlation analysis results showed that there was a very significant negative correlation between the browning index of total phenols, PPO, POD, PAL, SOD, CAT and APX activities of the 'Wen 185' green walnut fruits. 【Conclusion】 The Maturity Ⅱ (August 27) is a suitable harvest period for the 'Wen 185' green walnut fruits. Its browning is closely related to the total phenol content, PPO, POD, PAL, SOD, CAT and APX activities of green walnut fruits during storage.