In this paper, Prussian Blue (PB) thin films were deposited on indium Tin Oxide (ITO) transparent electrode using electro-deposition technique. The films are easily prepared by successive immersion of the substrates into an aqueous solution of FeCl3 and K4[Fe(CN)6]. The effect of the molar concentration during deposition process of the films is studied. The prepared films were subjected to electrochemical ion insertion using electrochemical cell containing 1M KCl aqueous solution. The electrochromic properties of samples prepared at different conditions were studied by transmittance and reflectance measurements. Films prepared at concentration of 0.04 and 0.05 possess a good electrochromic properties (Tv = 0.32 and OD = 0.28). However, films prepared at higher solution concentrations possess a low dynamic range (e.g. sample (M5) has Tv = 0.05 and OD = 0.07). X-ray diffraction show that the film prepared at a solution concentration of 0.04 which possess a good electrochromic properties is in the amorphous state. Also, SEM analysis shows that the sample prepared at a solution concentration of 0.04 has a small grain diameter (43nm).