Abstract: The calculation of the depths of field sources and the determination of the planar distribution of field sources based on the model for the decomposition of magnetic anomalies, power spectrum analysis and abnormal amplitudes indicate the effectiveness of multi-scale wavelet analytical method on potential field separation. In this paper, the method is applied to analyze and interpret the magnetic anomalies in the Beiya iron-gold mining district, Heqing, Yunnan. The emphasis is placed on the calculation of the depths of field sources of each order details and 4th-order approximation on the basis of power spectrum analysis, and the determination of spatial distribution of magnetic sources inferred from the abnormal amplitudes at varying depths. The results in this study show that the orebodies are responsible for highly magnetic anomalies in the northern and western parts of the Beiya iron-gold mining district, and display the modification in occurrence at the medium-deep parts of it. The wide ranges of magnetic anomalies in the eastern part of it are caused by the Permian basalts. The results outlined above may inspire some new approaches to the further deep-seated exploration and development in the study area.