The invention provides a wide-field CT (computed tomography) imaging method with different three-source circular orbit radiuses. The method has the features of multi-source CT imaging, allows an enlarged imaging field under same equipment and enables larger size object to be detected to be rebuilt. The method includes: a wide-field scanning mode with different three-source circular orbit radiuses and a backprojection filtration algorithm with no need for data rearrangement, wherein three fan-beam groups all have truncations, and initial phase differences of three ray sources are different; rebuilding precision is high, and rebuilding speed is high. This method can provide important theoretical basis and technical reference for the research and development of a three-source CT system.