Abstract: To explore movement law of biomass chars and ceramic balls mix flows in the incline tube with different cross-section shape，cold state PIV analog equipment was designed.Flow of ceramic balls （diameter of 1，2 and 3 mm） and biomass char with different mass ratio （10∶1，30∶1 and 50∶1） in three different cross-sectional shapes （circular，semi-circular half-square and square） of inclined tubes （X= 1190 mm cross section in steady flow phase） by PIV technique were studied.Results showed that：in the inclined tube with three different cross-section shape，the distribution of biomass char axial mean velocity in the yd = 0-1 range shape was similar to ‘hysteresis loop’.When mixing quality ratio was 10∶1，the biomass char axial mean velocity distribution was not affected by different cross-section shape，it could use square tube or semi-circular half-square tube instead of circle tube in experiments of inclined tube.When ceramic sphere diameter was 1 and 2mm，mixed particle mass ratio of 30∶1 and 50∶1，the biomass char axial mean velocity distribution was affected by different cross-section shape，it could not use square tube or semi-circular half-square tube instead of circle tube in experiments of inclined tube.