Thirty hybrids from ll parent sugarcance varieties in a incomplete diallel cross model were obtained．The seedling biomass of all F1S were analysed by a model of additive-dominance-random environment effect．The results indicated that the inheritance of sugarcane biomass was determined jointly by additive，dominance，and both additive and environm ent interaction effects, in which the additive effect was the most important one．The genetic effect of phenotypic characters from parents on the progenies was influenced mainly by female parent．Both broad-sense and narrow-sense heritabilities in biomass traits were relatively high． and the form er was higher than the latter，suggesting that the selection of biomass traits is effective in early generation．The analyses of additive and dominant effects predicted for parents and cross combinations showed that five parents, viz．YT72／426，YT79／177，YT85／177，ROC24 and ROC25 were accounted to have higher additive effect，and four crosses to have higher dominant effect，which could be used in sugarcane breeding for high biomass．