Based on the dry-wet season model of solar radiation for Yunnan (DWS model) developed by us and relevant data on geographic and meteorological parameters, we have estimated values of global radiation on tilted surfaces (south-facing) for each month at 133 meteorological stations in Yunnan Province, China, and have studied the ratios of global radiation on tilted surfaces to those on horizontal surfaces based on estimated data at these stations. It is believed that the ratio patterns are similar to those in other regions of the world.