Abstract: The polystyrene ultrathin films are prepared for two steps: first, modified polystyrene, such as sulfonated and carboxylic polystyrene, is synthesized from styrene, then their Langmuir Blodgett films(LB films) are made at the air/water interface. The technical conditions which affect the uniformity of the film are studied, also the thickness and the microtribological studies are performed on the films using atomic force microscope(AFM). For different polymer film materials, while the technical conditions are the same, the property of the film are different; as for the same polymer film materials, the condition of preparation of film will be changed regard to polymer relative molecular mass, conformation and polymer solution concentration. On the best condition of which is supplied in the paper, we get the sulfonated polystyrene and carboxylic polystyrene films which monolayer area are both 0.3 nm 2 and 0.7 nm 2, and the surface profile of the sulfuric polystyrene film of 20 nm are clusters by AFM.