Low dose radiation (LDR) induced products were extracted from mouse spleen and its biological activity was preliminarily detected. The mouse spleen cells were sonicated and the induced products in the lysate were obtained with centrifugation. The method of radioactive isotope incorporation was used and the DPM as an index for evaluating the biological activity of the induced products, To investigate the possible influences of variant factors on the activity of the products, tests were carried out under different conditions: different time for extraction, different radiation doses, different volumes of extracted products for stimulation, and different radiation modes. Results showed that the transformation ability of mouse spleen cells was significantly enhanced after stimulation of these cells with LDR—induced products. And the above—mentioned changes in experimental conditions could influence the activity of the induced products to different extents. It was indicated from this study that the active LDR—induced products could be extracted 2—16h after irradiation with a dose range from 5 to 15cGy, and the effective composition of the induced products maybe belonged to newly synthesized protein.