In this paper, the end-moraine dam is considered as a natural dam and the outburst of end-moraine lake is researched in terms of hydraulics and soil mechanics. According to field observations and previous researches, the study focuses on the overflow and piping-break types of outburst. It is found that the dyke breach in the overflow type usually has the shape of an arc or a trapezoid. From the field observations, the authors found a relationship between the height and the open width of the breach. Almost all end-moraine lakes collapse partially. Based on field surveys and sampling analysis, the authors determined the possible ways of collapse of the Guangxieco end-moraine lake by infiltration.