The scarce annual global solar radiation data of Henan Province were extended to recent 40 years (1960～1997) by experimental formula, and direct solar radiation and scatting solar radiation data were calculated by another experimental formula for the stations with the only global solar radiation data. Based on the above analysis, variation period of the solar radiation was found by the method of variance analysis, obvious decreasing trend of the global solar radiation of Henan was found. The direct solar radiation is also decreasing on the one hand, while on the other, the scatting solar radiation of north and south of Henan is decreasing. On the contrary, the scatting solar radiation of middle of Henan is increasing. The preliminary conclusion was drawn that the increase of the TSP concentration is an important reason for the decrease of the global solar radiation.