Abstract: In this paper inheritance of the chlorophyll content in immature skin of cucumber was investigated by applying the major gene plus poly—genes model of quantitative traits to a joint analysis of multi—generations(P₁、F₁、P₂、B₁、B₂and F₂)．The results showed(1)the immature skin color of cucumber Was mainly controlled by nuclear genes.(2)the chlorophyll content in immature skin of the cross of HYBP×JNQHG Was controlled by two major genes with additive-dominance effects plus polygenes with additive-dominance effects(the E-2 model)．(3)heritability values of the major genes of B₁、B₂ and F₂ population were estimated as 83.94% ，62.12%and 86.98%respectively,while polygenes of those were 7.23%,18.15%and 5.86%.The results demonstrated that the chlorophyll content level in immature skin of the cross was mainly controlled by two major genes mixed with the efect of polygenes．The estimated additive efects of the first major gene(d_a )was much higher than that of the second one db．There were obvious diferences in genetic efects between the two major genes．The efect of db was only about 35.51% that of d_a，indicating that
the contributions to the chlorophyl content level of the two major genes were not equal in the cross．The dominant efect of the two major genes，h_a and h_b were 2.7762 and 2.3392 respectively．

Key words: Cucumber, Fruit, Color, Chlorophyll, Inheritanc