The invention provides a pupil center-corneal reflection (PCCR) based sight line evaluation method in a sight line tracking system, belonging to the field of man-machine interaction. With specific to the main problems on user head motion limits and individual calibration in the traditional PCCR, the invention provides a method for compensating head positions under the conditions of a single camera and a single light source, which realizes the analysis compensation for influences of head positions variation to a pupil center-corneal vector, establishes an individual difference conversion model and further simplifies a calibration process to be a single-point process. Accordingly, a novel sight line evaluation method is developed; and in the method, the requirements of precise sight line evaluation on minimum hardware are decreased to be the single camera (uncalibrated) and the single light source, complex system calibration is unnecessary, natural head-motion sight line evaluation is realized, and user calibration is simplified to be single-point calibration. All links in the method meet the instantaneity requirements, and an effective solution to the sight line tracking system oriented to man-machine interaction is provided.