The flow in centrifugal fan and 90° bend pipe was simulated numerically by the RNG k-turbulent model in software Fluent, and obtained the distribution diagram of the pressure and velocity. From the distribution diagram of the pressure and velocity, for measurement, three measurement points must be chosen, and two of them should be closed to the wall of pipe. However, in order to insure the measure accuracy, five or six measure points should be chosen. In addition, the velocity distribution of pipe bending reaches well-distibuted at the 1000 mm away from pipe exports. That is fluid flowing after through the flow field of bending section tends to uniform soon, so for the greater curvature bend pipe, measurement is more convenient.