The invention discloses a structured light digital speckle interference device and method that can realize in-plane deformation measurement The device comprises a structured light illumination generating module, an imaging module and a data processing module Among them, the structured light illumination generation module includes a laser, a spatial light modulator, a TIR prism and a spatial mask The spatial light modulator is used to load stripe modulation patterns with different phase shifts along the first direction and the second direction respectively, so as to modulate the illumination beam, form a plurality of diffracted beams propagating in different directions and realize the phase shift operation; the spatial mask selects only + 1st, ‑ 1st diffraction order beams for interference to produce structural illumination light; the imaging module is used to record the digital speckle phase shift images corresponding to the structured illumination light in different directions and different phase shift amounts; the data processing module is used to obtain the deformation information of the sample along different in-plane directions. The invention can realize high-precision in-plane deformation measurement, is less affected by environmental disturbance, has a compact device and high stability.