Abstract: To explore the effects of straw mulching and biochar addition on soil temperature and maize yield, a field experiment was conducted following two-factor split-plot design, with two types of mulching (non-mulching, straw mulching) as main plots and three levels of biochar application (0, 4 and 12 t·hm^-2) as sub-plots. Maize grain yield, yield omponents, and soil temperature in different soil depths were measured. The results showed that straw mulching decreased soil temperature, with such effect decreased with increasing soil depth. Soil temperature showed a large change in the early growth period and a small change in the later period. Under different cover conditions, biochar addition had different effects on soil temperature. Under the nonmulching condition, biochar addition increased soil temperature, with the magnitude of such effect positively depending on application rates. Under straw mulching condition, biochar amendment resulted in a lower soil temperature in the 0-10 cm soil layer but an increase in 15-25 cm soil layer in vertical dimension. Straw mulching and biochar treatments significantly increased maize yield, yield composition and economic coefficient. The highest yield was achieved at the treatment of straw mulching incorporating with 12 t·hm^-2 biochar; this treatment increased grain yield, its components and economic coefficient by 24.2%, 6.4%-15.7% and 15% respectively, compared to the non-mulching and biochar-free treatment. Among all yield components, spike length and grain number had the greatest impacts on yield. Grain yield was negatively correlated with spike length and positively correlated with grain number.