The APV (AdaptivePhase/Doppler Velocimetry) system can be used to recognize the particle material andmeasure the particle size and velocity adaptively according to the Doppler frequency shiftand the Doppler phase shift theory. Through the light scattering theory of inconductivespherical particles, the layout of the APV system was studied, and the measurement methodof the flow field was discussed as well. The feasibility was proved with the simulatedexperiments.