Gas flow behaviour in co-current spray dryer is investigated numerically using the k-ε model of turbulent flow.The calculated flow fields are compared with previous experimental results. The distributions of the time average velocity and the intensity of turbulence are in good agreement for both values. The main flow region in the dryer is almost coincident each other. The main (axial) flow rate increases remarkably by acompanying the recirculation flow in the axial direction of the dryer. which reaches a maximum value of about 1.7 times the inlet flow rate. The particle trajectories obtained in the calculated gas flow fields are influenced colisiderably by the recirculation flow.