Abstract: Five cytoplasmic male sterile (CMS) and 6 restorer lines of rice were used as parents in an incomplete diallel cross design. Thirty cross combinations with the same growth period were selected as materials in the analysis of heterosis, combined ability and heredity of Cd. The main results were as follow: A negative heterosis was noted in brown rice Cd content. For the CMS and restorer lines, the general and specific combination abilities about Cd content were both significant at P < 0.01. This showed that the breeding of combinations with low Cd accumulation depended on both genetic improvements and evaluation of the parents. For the Cd content, heredity in the broadest and narrowest sense was 97.73% and 80.10%, respectively. This explained that gene additive function was the main in the genetic code of grain Cd content. The results suggested that chosen parents of the early generation were good.