The present disclosure provides a system for monitoring a scraper chain based on a measurement on transmittance of a torsion spring and a method thereof. The system includes a sprocket-wheel torsion detection device, a fixing device, a wireless receiver, an A/D converter and an industrial computer. In the method, the relative torsion of the two sprocket wheels is converted into the density change of the torsion spring, the light transmission area is converted into the current value by the laser sensing panel, a varying range of the torsion spring is calculated by the industrial computer through the preset threshold and its own program to monitor the operating conditions of the chain. The method has a novel concept, a stable and reliable system, and a high promotion value.