Polyaniline membrane is a conductive polymer, widely used as a current carrier for electrochemical and biological matters, and as a sensor. It is important to control the thickness of polyaniline membrane in measuring current of electrochemical reaction and beneficial to evaluate the quality and thickness of the membrane by using laser confocal scan microscope. After inputting 0.5ml of aniline and 355mg of Na<sub>2</sub>SO<sub>4</sub> into 25ml of pH2.0 buffer solution compound with HCl/KCl, a polyaniline membrane is deposited on a Pt wire of Φ0.8mm in diameter with the constant potential anode oxidation method in the CHI660b set, at a voltage of 0.75 Volt, the process of which takes 240 seconds. The polyaniline membrane is inspected with laser confocal scan microscope, at respective wavelengths of 488nm and 633nm. Then the various images are taken at 40×objective lens and different focal lengths. There are many light and shade stripes on the images, parts of which are closed, while others are unclosed curves. The polyaniline membrane is evaluated in terms of its width intervals of the stripes, thickness and uniformity, by means of image analyzing using the laser confocal scan microscope.