Modeling and experimental work on the auto-ignition of wood exposed to variable heat fluxes are presented. A one-dimensional model that describes the pyrolysis of wood subject to a linearly increasing heat flux was developed. Experiments were conducted for three species of wood subject to three levels of heat flux increasing rate. Reasonable comparative results are shown for in-depth temperature distribution. The thermal behavior of wood expose to variable heat fluxes is similar to that under low constant heat fluxes to some extent.