Based on the experiment research,it was compared that the inorganic polymer silicate with organic polymer such as polyvinyl alcohol(PVA),partially hydrolyzed polyacrylamide(PHPA),polyacrylamide(PAM) and kalium polyacrylate on the capability of instability prevention.The conclusion was drawn as following from the experiment.Firstly,the velocity of the film forming by adsorption and density of the protective foil were the key factors to determine the IPC(instability prevention capability) of the drilling fluid systems;secondly,the IPC of the drilling fluid systems was the result of synergistic action of the inorganic and organic polymers;thirdly,the IPC of PHPA drilling fluid system was better than PAM drilling fluid;finally,the addition of Na-CMC and PHPA could increase the density of the adsorbed film and improve the IPC of the system.