Mining and mineral exploration are very important in the global economy. In mining operations, communication systems play vital roles in ensuring personal safety, enhancing operational efficiency and process optimization. Multiple Input Multiple Output (MIMO) systems have been widely used in the mine environment to suppress the multi-path problem of the tunnel and enhance the capacity of the channel. In order to realize the optimal performance of MIMO system, spatial characteristics of wireless signal in an underground tunnel must be considered. In this paper, the wave propagation model combined with the modal theory and ray theory is used to simulate mine underground wireless channel. Meanwhile, the theoretical models of the signal Angular Power Spectrum (APS) and Angular Spread (AS) are constructed. After simulation and comparison, the following conclusions can be drawn: the APS distribution of the wireless signal is similar to the Gaussian distribution; the position of the antenna in the cross section of the mine tunnel has a small influence on the signal AS, which can be neglected; the roughness of the mine tunnel wall can change the characteristic of the signal AS to some extent.
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