The invention discloses a method for switching a grid-connected mode to an emergency autonomous mode of a comprehensive energy system. The method comprises the following steps: carrying out priority grading and priority grading on an electrical load and a gas load in the comprehensive energy system; establishing a fitness function, and determining an interruption sequence table of the interruptible load after splitting according to a solving result of maximization of a fitness function value; obtaining power vacancy caused by splitting in real time, and executing removal of the interruptible power-off load according to the sequence of the interruption sequence table; formulating a comprehensive energy system mode switching strategy; establishing a comprehensive energy system switching model; and solving the comprehensive energy system switching model to obtain a switching strategy, thereby realizing switching from a grid-connected mode to an emergency autonomous mode of the comprehensive energy system. Load characteristics of different time scales and different priorities in the comprehensive energy system can be fully utilized, and rapid switching of the comprehensive energy system from a grid-connected mode to an emergency autonomous operation mode is achieved on the premise that important safety constraints are met.