Abstract: Three-dimensional digital image correlation method (3D-DIC) is a new technology for optical mechanics measurements, which has the advantages of non-contact and full-field. In this paper, 3D-DIC method has been introduced into the stress test experiment of pure bending beam with electrical resistance straingauge method, and the dynamic resistance strain gauge and 3D-DIC non-contact measurement system have been used for synchronous measurement. Through experiments, the strain field of the selected surface area on the bending beam has been intuitively presented, and the strain distribution characteristic of the pure bending beam has been well observed. Comparing with traditional bending beam experiment in the mechanics of materials, the application of 3D-DIC method has expanded both the experiment content and the measurement technology. In our university, the expanded stress test experiments of bending beam using 3D-DIC method have been carried out in the secondary studies, such as students' innovation experiment, and satisfactory results have been achieved.