Carr-evaluation method for evaluating flow characterization of biomass particle straw has been studied to resolve the problem of testing flow characterization of crop straw. And the flow characterization of 8 types of crop straw came from North China was measured by the two methods of Carr-evaluation method and inner-friction angle method. The results showed that Carr-evaluation method can reflect the variation of particle straw flow characterization, the more score it had, the better flow characterization it was, and the 8 types of crop straws were divided into three categories, easy flow (such as the score of corn cob was 81), the general flow (such as corn stalks) and difficult flow (such as soybean), the results of Carr-evaluation method is similar to the results of inner-friction angle method.