This study describes the flow characteristics of solid-solid mixed particles in a cold two-dimensional moving bed. The results indicate that flow characteristics of mixed particles in the quartz sand–coal system are better than those in the cold CFB ash–coal system. The optimized conditions were obtained, θ2 = 20° and a heat carrier to coal ratio of 6:1. As the mixture progressed downstream, secondary separation of the heat carrier and coal become apparent. Furthermore, mixture residence times have been investigated to explore the relationship between regional residence times and to predict accurately the actual pyrolysis progress in pyrolyzer.