Behaviors of saturated fatty acid halides (CI4, C16, C18) were measured by LB method when the molecules were stimulated by pressure. The saturated fatty acid halides were deposited on the indium tin oxide(lTO) glass by the LB method. The average organic ultra thin film size and the surface roughness of the fatty acid halides thin films were investigated using AFM. It was found that AFM images show small surface roughness ($2.5{sim}5.0;nm$) and the organic ultra thin film size of $2.5{sim}12;nm$. Both aggregations and pin-holes were also seen on the AFM images. However we found that the surface roughness. These effects seem to be reasonable to be related to the increase of the organic ultra thin film size of fatty acid halides.