It is a big problem that the accumulation of heavy metals in wheat grains from in farmland soil contaminated with cadmium (Cd) and arsenic (As). Using biological simulation method, taking the soil in Cd and As compound polluted area as the research object, the experiment was conducted to explore the effects of biochar addition (C1 and C2 represented 3% and 6% biochar added in contaminated soil) on the accumulation and transport of Cd and As in the system contaminated soil-wheat/maize. The results showed that the addition of biochar significantly reduced the availability of Cd and As in the rhizosphere soil or non-rhizosphere soil in wheat season. And the average contents of Cd and As in wheat grains decreased by 19.25% and 50.70% compared with CK, but the difference was not significant for Cd. For the maize, the biochar treatments of C1 and C2 significantly reduced the contents of Cd and As in the ears, with a decrease of 85.67%, 61.28% and 98.36% and 96.48%, respectively. Furthermore, the biochar addition decreased the translocation and accumulation of Cd and As in the system of wheat-maize, but the treatments had no significant effect on the transport of Cd from straw to grain and Cd accumulation in wheat grains. In conclusion, adding 3% biochar in contaminated soil alleviated the contents of Cd and As in wheat grains and maize ears, and had a more obvious effect on the reduction of heavy metals Cd and As in maize ears. It was better pathway to reduce the translocation and accumulation of Cd and As in the system of contaminated soil and wheat/maize through addition of 3% biochar in soil.