The contact pressure distribution between components and polishing pads during the chemical mechanical polishing (CMP) of optical components is a critical factor that influences the polishing removal efficiency and polishing effect of components. However, it is difficult to obtain through simulations because the contact state between components, abrasives, and polishing pads is complex and changes continuously. In this study, a set of CMP surface-pressure distribution in-situ real-time detection devices is designed, and the thin-film piezoresistive sensors are arranged under the polishing pad in an array to detect the pressure distribution on the contact surface between the component and polishing pad in real time. Moreover, the theoretical model of the contact pressure distribution between the polishing pad and component surface is analyzed using simulations and compared with the experimental measurement results. Based on the experimental platform built independently, grinding experiments are conducted, and the surface shape of the polishing pad is measured using a Keyence CL-3000 laser displacement sensor. The experimental results show that with an increase in grinding time, the shape of the polishing pad surface gradually becomes flat and is close to the limit of the current grinding conditions. Its standard deviation decreases from 0.2079 to 0.1839 mm. The standard deviation of the regional pressure value measured using the pressure distribution detection device decreases by 8.2% and 0.2% in the first and second stages, respectively. The pressure distribution on the contact surface of the workpiece and polishing pad gradually become uniform, which corresponds to the trend of gradual flattening of the polishing pad surface. This study demonstrates that the proposed device can effectively detect pressure distribution and real-time changes during the polishing process.