The paper reports the experimental result of a kind of phosphor screen (Gd2O2S:Tb) which can be used to reinforce image. The phosphor screen has photon yield about 9×104 / MeV

and decay time of fluorescence measured by a single-photon-time resolution spectrometer is 833μs. The emission spectrum is obtained

which consists of a 545 nm main band surrounded by several weaker narrow bands. The experiment also shows that the phosphor screen has an afterglow component with a decay time of about one minute after natural light exposure.