Abstract: In the present study, the fast pyrolysis characteristics of sorbitol were deeply explored and the formation mechanism of the main products was revealed using fast pyrolysis experiments and density functional theory (DFT) calculations. The results show that the fast pyrolysis of sorbitol mainly produces low molecular weight products such as hydroxyacetaldehyde (HAA) and hydroxyacetone (HA), furan-based products such as furfural (FF) and 1-(2-furanyl)-ethanone (2-FE), and anhydrosugar product (isosorbitol (IS)). The yield of HA and HAA products is the highest, due to their lower overall energy barriers. Notably, the generation of HA and HAA are simultaneous. The formation of furan-based products 2-FE and FF needs to overcome relatively higher overall energy barriers, despite that some intermediates also appear in the formation of HA and HAA. Hence, the yields of furan-based products are lower than those of low molecular weight products. The reaction intermediates for formation of anhydrosugar IS are different from those of HA/HAA and 2-FE/FF. The overall energy barrier is high that leads to a very low yield of IS. This study provides a theoretical insight into the mechanism research and technique development for selective pyrolysis of sorbitol.