Particle image velocimetry (PIV) was applied to a spinning disc reactor, the instantaneous velocity distributions of flow filed on the spinning disc were obtained, and the effect of rotational speed and flow rate had been discussed. The experimental results revealed that the instantaneous velocity is firstly decreased and then increased from center to edge of the disc. The velocity field on disc center is controlled by flow rate, relative radial velocity increases with increasing flow rate. The velocity field on disc edge is controlled by rotational speeds, relative circumferential velocity increases with increasing rotational speeds. In the range of experimental conditions, critical radius (Rc) is about 50 mm, disc radius should be larger than Rc, appropriately.