Abstract: In order to find some solid state track detector materials with high sensitivity" for registration of light particles, we sifted a few kinds of cellulose acetate films made in China and found that the film base made by the Shanghai Film Works-among these films has the highest sensitivity. Furthermore, the effect of etching conditions on the relative sensitivity for a-particles was investigated in some detail, and an optimum etching condition was found. Under this condition, the sensitivity of the detector film to α-particle registration was determined to be above 8.78 MeV, exceeding the sensitivity of the previous cellulose acetate solid state track detectors and approching the sensitivity of the most sensitive cellulose nitrate solid state track detector available to date.