Crossbreeding of the elite clones is an important strategy to breed the new germplasms of Camellia oleifera capable of higher oil yield and quality. While the genetic control model and heterosis of oil-related traits in C. oleifera remains challenging. To improve the breeding efficiency, several genetic parameters were evaluated in this study based on a 5 × 5 complete diallel design of C. oleifera. A total of seven oil-related traits were measured for three years in the F1 progenies, including oil content of dry kernel (OC) and the contents of six kinds of fatty acid in the oil. For these seven traits, we calculated their parental general combining ability (GCA), special combining ability (SCA) and heritability. And the changed heterosis in F1 progenies during the growth period was analyzed. The results showed that the GCA and SCA of parents for most of the traits had significant differences among the crosses. And the ratio of GCA to SCA ranged from 1.67 to 2, meaning that the SCA was more important than GCA in C. oleifera breeding. The broad-sense heritability for the seven traits were from 11.74% to 53.38% and these traits were significantly affected by environmental factors. And the variation of heterosis were different at different traits. According to the assessed combining ability, heritability and heterosis, three parental combinations were suggested to use in C. oleifera crossbreeding, which harbored greater potential to produce the progeny with optimal oil-related traits. The cross CL4 ×CL40 was most apt to obtain superior progeny in terms of OC and C16:0. Whereas the cross CL4 ×CL53 would be also the better choice for culturing progeny with a high OC content. The cross CL10 ×CL53 and CL95 ×CL53 would be likely to beget superior progeny for the C18:1 and C18:2 content, respectively.