A system about 3D scanning measurement towards large objects without rails was developed in this paper, which combined binocular sensor with structured-light sensor together and achieved the unity of their coordinate systems through calibration. The double-line projection model was presented, through which the system can complete the stereo matching of the mark points in the binocular sensor and get mark points′ 3D coordinates. Based on the double-line projection model, a structured-light model named line-plane constraint was designed to get the modulated information of the light strips on the objects′ surface. In order to build the relationship between the sensor coordinate system and the global coordinate system, the property of the space geometrical invariability of the mark points was used. In this way, the entire system of the sensor can convert the 3D points cloud data measured at different locations to the global system in real time. Thus, the entire sensor system can complete the 3D scanning measurement of the object, the measurement precision was better than 0.08 mm within the working distance.