Abstract: The experimental method for detecting alpha radioactivity using autoradiography with phosphor screen was introduced in this paper. The influences of some parameters, such as the distance between the sample and the phosphor screen (or referred to solid angle), the exposure time and the radioactivity in the sample, on the light intensity of the phosphor screen image were studied. It is shown that the light intensity after solid angle revision does not vary significantly from one geometry to another. The intensity is proportional to the exposure time and the amount of activity in the sample before the phosphor screen is saturated. In addition, several experimental issues should be paid attention to be discussed, including the exposure condition, the number of scans, the background of the phosphor screen, the influence of the gamma or X-ray and the status of the sample.