Moraine Lake outburst is a common geological disaster in Tibet. Meltwater infiltrates into glacier through the cracks and lubricates it, increasing the instability of glacier. There is a close relationship between glacier landslide and Moraine Lake outburst. In order to explain it, we established the glacier sliding model, and analyzed the sliding characteristics. Then we discussed the link between glacier landslide and Moraine Lake outburst, and then proposed a quantitative expression. Finally we analyzed the glacier stability of Aya Moraine Lake and others, forecasted and evaluated the risk degree of Moraine Lake outburst. Field investigation conclusions are consistent with calculated results, that is to say, the calculated results are accurate and the predictions are reasonable.