The severe overlapping of particle tracks seriously affects the measurement accuracy of particle track. A new method is proposed based on track overlapping classification to separate and measure the severe overlapping of particle tracks. Firstly, the overlapped tracks are classified according to the inclusion of particle track centers to identify the severity of particle overlapping. Then, the non-overlapping particles are scaled to half to form structural units. The finite erosion operations are applied to the severely overlapped particle tracks based on these structural elements. These particle tracks are separated, and form four kinds of track classification images. Experimental results show that these severely overlapped particle tracks can be separated by combining track overlapping classification and finite erosion operations, which can eliminate the influence of track overlapping on the image measurement accuracy.