The invention relates to an ultrasonic guided wave defect imaging method for impact damages of a carbon fiber composite material. An ellipse positioning imaging algorithm comprehensively utilizing the defect reflection echo signal time and amplitude full wave information based on an ellipse positioning process is provided. The algorithm utilizes an ultrasonic transducer array to obtain defect reflection echo information in different paths, and the signal arrival time and the amplitude information of a signal are accurately extracted by applying complex wavelet transformation, so the imaging of hole defects in a metal plate and a carbon fiber-epoxy resin composite plate is realized. Influences of the sampling interval and the signal-to-noise ratio of the signal allow a CT (computed tomography) algorithm which directly adopts the original signal amplitude to have low precision of the imaging result, so the envelope improved imaging algorithm based on the complex wavelet transformation is introduced in the invention. The envelope improved imaging algorithm can realizes the defect imaging only through six transducers, and the detection precision is improved by applying the complex wavelet transformation, so the accurate quantified detection of impact damage defects of the composite plate is realized.