Abstract: A numerical method has been developed to simulate the flowfield of the helicopter rotor,fuselage and the combination of them in forward flight.In this method,unstructured embedded grid technique was used to simulate the position transformation relationship between the rotor and its fuselage,the three-dimensional unsteady Navier-Stokes(N-S) equations were discretized by a second-order upwind finite-volume scheme and the lower-upper symmetric Gauss-Seidel(LU-SGS) scheme was employed in time-stepping.A new method was given to solve the problem of the "donor searching" when the space between the rotor and its fuselage was too narrow.Based on this model,the flowfield of the single rotor,fuselage and the combination of them were calculated,the comparisons of the calculated results with the experimental data indicate that the present method is very effective to analyze the helicopter flowfield in forward flight.