With Si(Li) X-ray energy spectrometer, the intensity of low-energy radioactive source 55Pe has been measured and the absolute characteristic curves of emulsion for 5F medical film and Kodak No-screen film under the condition of 55Fe radiation have also been obtained using time-mark exposure technique. When the optical density D of 5F film is equal to 1, then the corresponding exposure H is equal to 12 × 107 photo/cm2.