Background <p>Photo-curing, thermal-curing, and photo-thermal-coupled curing have been widely used in various engineering fields. However, the service quality and life of these cured polymer materials are dramatically impaired by the curing stress evolved during the curing processes in practice. Existing measurement methods face limitations such as lack of dynamic monitoring, complex procedures, and applicability to only a single curing process.</p> Objective <p>This study aims to develop a new instrument for measuring the curing stress evolution and controlling curing conditions during photo-, thermal-, and photo-thermal-curing, while also validating the measurement accuracy. Accordingly, the stress development under different conditions was investigated, with mechanisms systematically elucidated.</p> Method <p>A cantilever beam-based setup was integrated with a temperature control system to enable real-time stress monitoring under various curing processes. The curing stress evolved during the various curing processes was measured under different working conditions (instrumental stiffness and sample thickness).</p> Results <p>Based on the newly-developed instrument, the stress evolution under various curing processes can be accurately captured. The stress magnitude increased with both instrumental stiffness and sample thickness. The photo-curing stress was primarily dominated by the polymerization shrinkage. The thermal-curing stress was driven by a combination of the thermal expansion/shrinkage and the polymerization shrinkage. Photo-thermal stress resulted from the interaction between the photo-curing and thermal-curing mechanisms.</p> Conclusions <p>This study presents a unified instrument for the curing stress measurement during various curing processes and provides insights into the mechanisms of the stress development, offering valuable guidance for improving polymer curing and material performance.</p>