We have developed a continuous model to describe the inclination of a dislocations near a free surface in BCC crystal. In this model, an energy variation equation is set to obtain the force balance between the effect of energy difference in different lattice orientation and the influence of the free surface. As a result, the relationship between the inclination angle of the dislocations and the tilt of the burgers vector is given. We have also numerically simulated our model with Molecular Dynamics method, which verifies the validity of our model for the results from coutinuous model matches with the numerical simulation.