The work aims to build a real-time detection platform of electroforming stress to evaluate the measurement accuracy and verify the variation laws of the average internal stress of the nickel coating in the process of electrochemical deposition. Lateral shear wave front sensor was used to build a real-time detection platform of electroforming stress and then calculate the average stress of the electroforming layer with Stoney formula by measuring the radius of curvature of electroformed substrate under the electroforming layer stress. A reference spherical mirror was adopted to evaluate the measurement accuracy of the radius of curvature of the lateral shear wave front sensor, and the average stress measurement limit and the detection accuracy of the electroforming layer were evaluated by carrying out real-time detection experiment to the internal stress of electroforming layer under the current density of 0.5 A/dm2 and the detection error was analyzed at the same time. The measurement accuracy of radius of curvature of lateral shear wave front sensor was 99.22%. Under the current density of 0.5 A/dm2, the measureable minimum thickness of the real-time detection platform built for internal stress of electroforming layer was 5.1 μm, and the measurement error of internal stress brought by fluctuations of measured curvature was 1.3 MPa. The experiment illustrated that the thicker the electroforming layer was, the more intensified the average stress of electroforming layers was. When the thickness of the electroforming layer reached about 30 μm, the average stress of electroforming layers was stabilized, with the stress of 79.7 MPa. Meanwhile, if the thickness of layer was under 30 μm, the average stress of electroforming layer along the length of electroforming base was much more intensified than that along the width. As the increasing of the thickness of the electroforming layer, the average stress of electroforming layer in two directions tended to be the same. The real-time detection platform for internal stress of electroforming layer built by a lateral shear wave front sensor can effectively carry out high-precision real-time measurement to the stress of electroforming layers, which provides a detection basis for the study of stress variations in the process of precision electroforming.