The cold state PIV analog equipment was designed to explore the movement law of the biomass chars and ceramic balls mix flows in the down flow reactor. By simulating the cold state, the stability and continuity of the equipment of ceramic ball and biomass char, the equipment implements even, precise and continuous down the mix of two particles were tested; it satisfied the requirements of the two particles different mass proportions in the experiment; by testing, the equipment can satisfy the experiment; many bright and white stripes formed by the light’s reflection and refraction in two sides of the round tube axes in PIV were avoided by using the biomass char, and the veracity of data were greatly enhanced.