The present disclosure relates to the field of early warning for geological disasters, and discloses an early warning method for icefall-caused moraine lake outburst disasters, which aims at solving the problems of low early warning precision and difficulty in implementation in an early warning solution of the prior art. The method includes: S1, calculating topographic parameters of moraine lakes and upstream glaciers thereof, and filtering a moraine lake to undertake focal monitoring; S2, calculating a freezing-thawing cycle index and a regional accumulated temperature index of an upstream glacier region for the moraine lake to undertake focal monitoring, S3, calculating a catastrophic climate determination factor TG-year, wherein if the catastrophic climate determination factor TG-year satisfies a corresponding catastrophic climate determination condition, an early warning condition is satisfied, otherwise the early warning condition is not satisfied; and S4, implementing early warning.