The effects of biochar application on selenium forms and bioavailability in selenium-enrich soil in red soil region were studied， in order to provide a theoretical basis for selenium activation and efficient utilization of selenium resources in selenium-enriched soil. In this paper， a pot experiment was conducted with four biochar adding levels at 0.0%(CK)， 0.5% (T1)， 1.0% (T2) and 1.5% (T3) of soil weight. The effects of biochar addition on soil selenium forms and maize selenium nutrition were consecutively analyzed with three batches of maize seedlings. The results showed that the content of soluble selenium with T1， T2 and T3 was increased by 0.46， 0.42 and 0.43 percentage on average， respectively； exchangeable selenium was increased by 0.61， 1.66 and 1.50 percentage on average， respectively， after biochar application. The proportion of iron-manganese combined selenium was decreased， the proportion of organic matter-bond selenium was decreased and then increased gradually， while the proportion of residual selenium was increased and then decreased gradually. The selenium content of maize root was significantly positively correlated with the contents of soluble selenium， exchangeable selenium and available selenium of soil， while the selenium contents of maize stem and leaf were not related to the different forms of selenium in soil. Biochar application could increase the selenium accumulation in maize plants， and T1， T2 and T3 treatments were increased by 10.03%， 31.30% and 21.21%， compared with CK， respectively. In conclusion， applying biochar can effectively improve the selenium bioavailable in red soil and promote the accumulation of selenium in plant， among them the effect of adding biochar at 1.0% of soil weight is the best.