In order to explore the excellent germplasm resources of Cucurbita pepo L. and improve the selection efficiency of tender fruit appearance quality， this study classified the skin color of tender fruit using colorimeter in 54 self-bred lines of zucchini developed by our unit. Based on seven representative lines （including four key lines）， the correlation between chlorophyll synthesis metabolism and its skin color formation was analyzed. The results showed that chlorophyll was the main pigment that determined the skin color such as partial white， light green， emerald （vivid） green，green and dark green. The chlorophyll a accounted for 49.20% to 60.58% of the total chlorophyll content， as the main determinant for the deep and light skin color. The emerald （vivid） green skin with the most vibrant and greenish color had significantly higher chromaticity value （C） than other skin color， while chlorophyll a/chlorophyll b and the red green value （a^*） were significantly higher and lower respectively than those of partial white， light green， and dark green. The synthesis of chlorophyll in lines with dark green， emerald （vivid） green， and partial white maintained two bottlenecks： PBG to Urogen III， and Coprogen III to Proto-IX. However， the latter transition stage was the main reason in the chlorophyll synthesis blocked， and sudden decrease of chlorophyll content of partial white and emerald （vivid） green. There was a significant correlation between chlorophyll synthesis weaken and chlase in chlorophyll metabolism enzyme activity enhance degradation， superoxide dismutase （SOD） and catalase （CAT） activities weaken， those also the reason of partial white skin color. SOD and CAT activities in antioxidant enzymes were significantly correlated with the chlorophyll content of the skin of tender fruit， thereby SOD and CAT delaying the rate of chlorophyll reduction in emerald （vivid） green and dark green. This study provided theoretical basis and technical support for in-depth analysis of different skin color of tender fruit especially the color formation mechanism of emerald （vivid） green， and for the exploration and utilization of relevant excellent and specific resource materials.