According to rock analysis of X- ray diffraction, scanning electron microscopy and isothermal adsorption experiments on Lower Silurian Longmaxi shale cores samples from 11 gas wel s in Changning-Weiyuan area in the southern part of Sichuan Basin, the adsorptivity and its influential factors are statistical y analyzed. Combined with a large number of measured data of gas content in shale, it is shown that stratigraphic factors commonly exert their influences on adsorption through changing the gas generation amount and the extent of adsorbing active surface area in shale. The stratigraphic factors mainly include hydrocarbon generation conditions such as TOC(0.17,~4.3,), type of organic mat er (Type-Ⅰor Type-II1) and maturity(2.4,~3.0,), and reservoir conditions such as mineral composition, pore volume(3.0,~6.0,) and structure(mostly mesopores) and humidity. External factors, such as pressure and temperature, exert their definite influences on the adsorption capacity of Longmaxi shale through changing activation energy and binding energy of gas moleculars.