At present, accurately measuring the thiekness of liquid thin films remains challenging,especially forfragile soap films.Such measurements require nondestructive and high-precision optical instruments, which areevidently impractieal for routine applieations,ln this study , we propose a method for measuring the thickness olsoap films using light interference , offering a precise yet relatively practical approach for determining thethickness of micro/nano-seale liquid films.Due to the inluenee of gravity ,soap films typically exhibit a thinnetop and a thicker boltom. When illuminated by vertically ineident light , interferenee fringes of equal thicknessappear across the film,By measuring the distanee of these fringes from the upper edge , the local thiekness of thefilm relative to its topboundary can be obtained via intererenee techniques.ln this work, we measured therelative thickness distributions of soap films formed on plastie rings of three different shapes at various timepoints, analyzing how thiekness varies with verical height, Additionally, using a refined Michelsoninterferometer and the prineiple of equal inelination interference under monochromatie light , we determined theaetual thickness at the center region of the soap film,This method enables the measurement of thickness atvarious positions of a soap film , providing a referenee teehnique for measuring the thickness of other liquid.based thin films.