Based on the principle that natural gases in pores of rocks cause the redaction of porosity in dielectric log and growth of porosity in density log, tnts paper has brought forward a new dcal density superimposition gas-search method, which can get rid of the influence of thelithologic character and raise the resolution power in logging gas-search work and the degree of audiovisualization in the evaluation of the gas layer. When used in the search for gas reservoirs in lowporosity dolomite of the Shaaoxi-Gansu -Ningxia basin, this method yielded obvions geological effe ets. It can also be used in search for gas reservoirs in other rocks that bort natural gases.