Abstract: The radial velocities of wide spaced two jet and four jet impinging streams have been measured by Dual PDA with different nozzle diameters and primary velocities. Results show that the distribution of radial velocity of wide spaced two jet and four jet impinging streams has relation to d/L , the maximum radial velocity has relation to u 0 d/L , and the radial distance of the position of the maximum radial velocity is directly proportional to L .