Abstract: The autoradiography behaviors of three kinds of radionuclides ²⁴¹Am, ¹⁴C and ¹³⁷Cs on three types of phosphor screens (PerkinElmer Co.) have been studied. A method has been provided to estimate the upper limit of exposure time with the aim at avoiding the saturation of screen. All the three types of screens show good linearity to alpha, beta or gamma radiations before saturation. It is common that the stored signals of phosphor screens fade with time after irradiation, with higher speed at first and lower speed afterwards. It is recommended that the screen be scanned immediately after irradiation.