Pollution sources monitoring data reflect the pollution discharge of enterprises and the impact of pollution discharge on the quality of surrounding environment, and are also the key evidence for administrative organs to conduct environmental supervision and administration and for judicial organs to determine whether the parties concerned have illegally discharged pollution in environmental cases. However, in practice, due to the qualification problems of monitoring institutions and monitoring personnel， the serious falsification of monitoring data caused by poor supervision and the difficulty of forming a complete evidence chain by using monitoring data as isolated evidence，the evidential validity of pollution sources monitoring data as evidence for identifying illegal pollution discharge of enterprises is questioned. Therefore, in order to give full play to the evidential effect of the monitoring data of pollution sources, the legislation shall be perfected, specifying the qualification accreditation standards for eco-environmental monitoring institutions in the legislation, realizing the whole-process supervision on the environmental monitoring of pollution sources, and imposing heavier punishment on the acts of falsifying the monitoring data， so as to make the monitoring data of pollution sources better serve the administrative organs’ management of pollution discharge of enterprises and the judicial organs’ handling of environmental cases.