Total 24 hybrid combinations were formulated by NC II design using hybrids (J. sigillata x J. regia) Yunxin 7926 (P11), 8064 (P12), 8034 (P13), 7914 (P14) as female parent and 6 superior trees of J. sigillata from Sichuan as male parent. The combining ability and heritability of walnut characters were studied, including diameter, weight, thickness and rate of kernel. The result shown that: both additive variation and non-additive variation were significant in these 4 characters, but the additive variation was principle. Different parent had different excellent genes. P24, P23, P22 and P14 were the best parent to improve walnut diameter and weight, followed by P21, P13 and P11. In contrast, P25 and P26 shown poor effect on diameter and weight. Cross P11xP23, P11xP24 and P12xP24 were good for increasing diameter, while cross P11xP26 was the best in increasing rate of kernel. The broad-sense heritability was ordered from high to low as diameter (0.990)>thickness(0.968)>rate of kernel (0.970)>weight (0.968) and the narrow-sense heritability was ordered as diameter (0.844)>thickness (0.821)>weight (0.735)>rate of kernel (0.693).