The invention discloses a 3D (three-dimensional) sight direction estimation method for robot interaction object detection. The method comprises steps as follows: S1, head posture estimation; S2, mapping matrix calculation; S3, human eye detection; S4, pupil center detection; S5, sight direction calculation; S6, interaction object judgment. According to the 3D (three-dimensional) sight direction estimation method for robot interaction objection detection, an RGBD (red, green, blue and depth) sensor is used for head posture estimation and applied to a robot, and a system only adopts the RGBD sensor, does not require other sensors and has the characteristics of simple hardware and easiness in use. A training strong classifier is used for human eye detection and is simple to use and good in detection and tracking effect; a projecting integral method, a Hough transformation method and perspective correction are adopted when the pupil center is detected, and the obtained pupil center can be more accurate.