Starting from the plane angular spectrum theory, we establish a transmission model of beam refraction at the interface between air and glass. Based on this model, we reveal a transverse angular shift in the optical Magnus effect. For a certain linearly and elliptically polarized light beam, the field centroid of refraction beam exhibits a transverse angular shift. However, the transverse angular shift would vanish when the incident light beam is circularly polarized. At an interface between positive and negative refractive indexes, the transverse angle shift presents a reversed phenomenon which is caused by negative diffraction in the left-handed materials. Ultra-high refractive index can significantly reduce the transverse angular shift. On the contrary, the ultra-low refractive index can significantly enhance the transverse angular shift. These findings provide a new method of how to adjust and enhance the optical Magnus effect.