Abstract: The attenuation coefficient of polyethylene material is smaller than that of metal material and theoretically it is possible to use a ray detection method. Through the experiment, in which the appropriate number of exposure pulses and focal lengths were selected, three kinds of artificial defects in soldered joint of buried polyethylene pipes were tested by radiation and it was found that the detection rate for volume type defects was high, whereas it was difficult to detect the area type defects. It is shown that ray detection is applicable while detecting volume defects in soldered joint of polyethylene pipes.