Abstract: Considering the importance of noise monitoring for environmental noise prediction and management, a sound source monitoring method based on sound intensity measurement is proposed and applied to environmental noise prediction and noise contribution analysis of power plant boundary. The measuring points are arranged near the noise sources of the main equipment of power plant, and the radiated sound intensities of the workshops installing the equipment are measured and calculated, then the workshop is simplified as a surface sound source to establish a noise prediction model with the measured and calculated sound intensity level as the source intensities of the model. The model is used to calculate the A-weighted sound pressure levels at the prediction points of plant boundary, which are in good agreement with the experimental values. Therefore, the data reliability of the sound source monitoring method and the correctness of the noise prediction model are verified. Through the calculation and analysis of the model, the contribution and effect of the main noise sources of power plant on noise emission of plant boundary are provided, which could be a technical basis for noise control of power plant.