Study on the mechanism of droplet transport and the droplet eddy diffusivity in the intake manifold of internal conbustion engine with carburetor has been carried out in this paper The theory and experiments were studied and performed respectively, to elucidate the mechanism and to measure typical rates of deposition, on the walls of a straight type intake manifold, of water droplets suspended in a turbulent air streams. Accordingly, the results are that Mechanism of a spray transport to the walls is caused by the fluctuation component of radial velocity. Deposition rate of a spray on the walls is mainly dependent upon air velocity and mean diameter of spray, and Droplet eddy diffusivity in the intake manifold is around $80sim105cm^2/sec$.