There are many biosurfactant substances in human urine, and the adsorption relationship between these substances and calcium oxalate crystallites with different morphologies has not received widespread attention. In this study, the commonly used anionic surfactant sodium dioctyl sulfosuccinate (AOT) was selected as the adsorbing substance. The adsorption differences of AOT onto calcium oxalate dihydrate (COD) with different morphologies were studied to calcium oxalate stone’s formation mechanism. The crystalline phase transition of COD with different morphologies (Rod, Blunt, Flower, Cross, Bipyramid) before and after AOT adsorption was analyzed using an X-ray powder diffractometer Fourier-transform infrared spectrometer. Zeta potential changes on crystal surface after AOT adsorption was measured using a Zeta potential analyzer. The adsorption quantity of different AOT concentrations onto various COD crystals was detected using a colorimetric method, and the adsorption curves were drawn. As c(AOT) increases, the number of COD adsorbed increases gradually, and finally reaches saturation, and the adsorption curves are all S-type. The order of maximum adsorption of AOT by different morphologies of COD is: COD(Rod) (41.0 mg·g-1)>COD(Blunt) (37.5 mg·g-1)>COD(Flower) (35.0 mg·g-1)>COD(Cross) (27.2 mg·g-1)>COD(Bipyramid) (20.9 mg·g-1). The larger the specific surface area of the COD crystal was, and the more active sites were provided, so the stronger the adsorption capacity would be; the (100) surface of COD, which is rich in Ca2+ ions, is beneficial to AOT adsorption; the larger the internal energy of COD crystal was, the lower the adsorption amount would be. COD crystals’ stability in suspension adsorbed is obviously increased after AOT adsorption, and the rate of COD transition to COM is obviously reduced. Based on the adsorption characteristics of AOT on the surface of COD crystals with different morphologies, we propose a molecular model for the adsorption of AOT onto COD crystals. The adsorption of AOT by COD crystals is closely related to crystal morphology. The morphology of COD crystal that easily adsorbs AOT is more likely to adhere to injured cells’ surface with negative charges, thus leading to an increasing risk of calcium oxalate stone formation.