In order to investigate the influence of divergent ratio on the flow and heat transfer characteristics of half-corrugated microchannel, five models of half-corrugated microchannel with different divergent ratio were designed, flow (200＜Re＜1000) and heat transfer behavior were researched by numerical simulation method, and the results were compared with smooth microchannel. The results show that the pressure drop and Nusselt number of half-corrugated microchannel increase with the decrease of the divergent ratio. Compared with smooth microchannel, half-corrugated microchannel has better heat transfer performance but higher pressure drop loss. By introducing η as the comprehensive performance index, it is found that reducing the divergent ratio is an effective way to improve the comprehensive heat transfer capacity of the half-corrugated microchannel. And when the Re＞490, its comprehensive heat transfer capacity is better than that of smooth microchannel.