Abstract: In order to study the velocity distributions of the mixture flow for ceramic balls and biomass chars in incline tube reactor, the flowing characteristics of mixture in incline tube were measured by using particle image velocimetry (PIV), and different quality ratios (10:1, 20:1, 30:1, 32:1, 40:1, 50:1 and 60:1) of ceramic balls with diameter 1mm to biomass chars were used in the experiments. The experimental results showed that the mixed flow was composed of three phases, which were disordered flow (0～590 mm), transition flow (500～590 mm）and steady flow (≥590 mm) respectively. In the steady flow phase, the axial velocity increased when the ratio of ceramic balls to biomass chars increased. At different sections and different mixing ratios, the axial velocity distributions were similar and the radial velocities were all less than 0.2 m/s. The results can provide theoretic references for the study of heat transfer law of the mixture flow of ceramic balls and biomass chars in incline tube.