Based on the the general expression of the beam wander variance modeled by Andrews and Philips, the expression of wander variance for partially coherent Gaussian-Schell model beam considering the outer scale was derived using beam width formula of partially coherent Gaussian-Schell model beam propagating in slanted atmospheric turbulence, combining the turbulence structure constant model varying with height, numerical calculations were conducted and the spreading and wander variance of partially coherent beam and fully coherent beam were comparatively analyzed. The results show that, compared to the fully coherent beam, the partially coherent beam spreads faster and is less affected by turbulence under the same propagation conditions, and the beam spreading effect becomes weaker as the initial beam radius becomes larger or the height of the receiver becomes higher. As the propagation distance increases, the beam wander variance decreases with the increase of initial beam radius, the beam wander variance caused by different coherence have little difference. The wander of fully coherent beam is less affected by the wavelength, while the longer the wavelength of the partially coherent beam, the more obviously the beam wanders.