For steady state binary nucleation, the directions of the nucleation flux and the nucleation force are obtained in the whole size space. The derivation of the directions is made possible by introducing a local coordinate axis system along the streamlines of the nucleation-force vector and by employing the assumption of local uniformity for the direction of the streamlines. For an ideal hexanol-ethanol system, the results predicted by our theory agree with the numerical results. For a specific nonideal system (PD2), our theory fails to apply to the region where our assumption is posteriorly invalid. In this case it may be necessary to consider the variation of the direction of the force.