The coherence theory of the non-stationary light field is combined with the generalized Huygens-Fresnel diffraction integral to investigate the evolution of spatiotemporal coherent vortices (STCVs) during the propagation in a dispersive medium. The expression of the mutual coherent function of partially coherent pulsed beams with STCVs at the propagation distance z is derived, and the mathematical and physical description of the STCVs is obtained. The results show that a coherence switch of STCVs occurs during the propagation in the fused silica medium. The spatial coherence width and temporal coherence length of the pulsed light source can be regarded as the control parameters of the coherence switch to control the transmission of STCV information. The size of the coherence switch area depends heavily on the propagation distance. The size of the coherence switch area is large when the propagation distance is short, otherwise, it is small. Moreover, an optical communication model based on a coherence switch is designed.