Measuring the refractive index of transparent solids and liquids is an important content in middleschool physies experiments. The visitation method for measuring the relractive index of liquids has beenimproved by some published literature, that is ,the length of images of an objeet caplured by a smart phone inthe condition of without water, with water and foating on the surface of the water is employed by the" IMAGEME"T"ER" software,and is used to replace the ratio of actual depth to visual depth with the ratio ofimage length in three cases.The reraetive index of water can be caleulated from this.lt is thought that waterdepth , the inelination of the mobile phone and the distanee between the mobile phone and the water surfacemay affeet the measurement results. The control variable method is used to explore the influenee on themeasurement of water refractive index in this work.After comparing with the standard value of water refractiveindex ,the best experimental conditions are obtained.