The principles of CINRAD velocity measurement are addressed in detail and systemically，and the questions of velocity ambiguity，as well as their reasons，are discussed.Based on these analyses，two methods for correcting ambiguity are introduced：theoretical value through velocity demarcation and true value displayed while velocity ambiguity occurring.Several precision test methods of different types of CINRAD are introduced and compared mutually， and their merits and demerits are given，which can be used in the technical assurance for CINRAD.