Compared with magnetic switching by an external magnetic field or by a heat-assisted manner, all-optical switching (AOS) can complete the switching process within 100 ps, which has attracted extensive attention from researchers. Among the magneto-optical materials which can realize AOS, the ferrimagnetic GdFeCo has the ability to realize single-shot AOS and possesses great potential in all-optical magnetic storage. In this paper, a microscopic three-temperature model (M3TM) is utilized to simulate the AOS process of GdFeCo, which is also demonstrated experimentally, under the excitation of a single laser pulse based on the heating effect. By using this M3TM, the AOS dynamics and the final magnetization states of GdFeCo induced by single laser pulses with different energy and pulse widths are calculated and analyzed concretely. Compared with the atomic spin model and the Landau- Lifshitz-Bloch (LLB) model, M3TM provides a more concise time-varying expression of the magnetization of GdFeCo and explicitly addresses the dissipation of angular momentum after the laser-pulse excitation, which enables faster calculations of the heat-induced magnetization dynamics in magneto-optical materials with large areas.