The present disclosure discloses an apparatus for measuring an internal strain field of a dental resin, comprising: an optical measurement system, a probe and a data processor, wherein an optical fiber coupler in the optical measurement system has one input terminal connected to a light source, one output terminal connected to the probe, the other output terminal provided with an optical component including a reflective element for forming reference light and the other input terminal provided with an photoelectric imaging apparatus for receiving interference light formed by object light and the reference light. The probe is configured to irradiate detection light outputted from the optical fiber to a measured tooth and receive object light which is reflected by the tooth and the data processor is configured to obtain a measurement result of the internal strain field of the measured dental resin according to an interference spectrum obtained through imaging by the photoelectric imaging apparatus. The apparatus for measuring an internal strain field of a dental resin according to the present disclosure achieves online measurement of a distribution of the internal strain field of the resin based on the interference tomography measurement method, so as to detect an internal defect of the resin according to a change of the internal strain field of the resin under a stress.
