Shale gas is a kind of unconventional gas resource stored in free and adsorbed states in the organic-rich shale system. The horizontal well productivity is mainly controlled by the free gas and adsorbed gas ratios. The measurements and influencing factors were detailedly reviewed and the dual-porosity of Eclipse and logarithmically-spaced grid refinement method was used to establish a shale gas horizontal well geologic model. Five cases with different free gas and adsorbed gas ratios were designed and simulated to analyze the horizontal well productivity. The horizontal well gas production, cumulative gas production, free gas and adsorbed gas production, free gas and adsorbed gas recovery factors, formation pressure distributions were provided. The research shows that with the increase of free gas ration and the decrease of adsorbed gas ration, the horizontal well daily gas production and cumulative gas production increase. Almost all the gas produced in initial stage is free gas and adsorbed gas is mainly produced in the middle and late stages. The free gas recovery factor is relative higher than that of adsorbed gas. High daily production and cumulative production can be gained with a large free gas ration in the development of shale gas reservoir.