Tungsten trioxide square nanosheets were prepared via acid-assisted one-pot process. Morphology structure and homogeneity of the materials were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM) and ultraviolet-visible diffuse reflection spectrum (UV-DRS). According to the X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis of the elements and states in the material, the tungsten trioxide nanosheets were successfully prepared and some oxygen defects were found on the surface. Using this material as the surface-enhanced Raman scattering (SERS) substrate, different concentrations of crystal violet (CV) was detected, and the relative standard deviation (RSD) value of 917 cm-1characteristic peak was 16.13%, indicating that the substrate had high repeatability.