Shanwang spring natural soda water occurred in vesicular basalt rocks in Niushan formation of Linqu group. Its water quanlity is good and has vast exploitable prospect. In this paper, by using high pressure reaction kettle, actual forming conditions of water and rock reaction balance has been simulated. At the same time, with the Isotopic analysis, X-ray diffraction analysis and other means, combining with local special hydrological and geological background, the formation mechanism of soda water has been introduced systematically.