A pot experiment was conducted to study the effects of adding rapeseed straw biochar on soil chemical properties and rice seedling growth. The results showed that adding biochar significantly increased pH value and organic matter content of the soil, but did not significantly affect total nitrogen and alkali-hydrolyzable nitrogen contents in the soil. Adding biochar significantly increased root activity, total root length, total root surface, total root volume, number of tillers, leaf area, leaf chlorophyll content, dry matter of rice. In summary, adding biochar is beneficial to improve soil fertility and consequently promote root and shoot growth of rice seedlings.