Sludge dewatering is a matter of great concern to reduce the volume of sludge, stabilize its organic components, and achieve resource utilization. This study investigates sludge dewatering by microwave torrefaction along with the production of sludge solid biofuel at 480–800 W combined with durations of 5–25 min. Proximate analysis, calorific value analysis, thermogravimetric analysis, and scanning electron microscopy observations are employed to evaluate the dewatering degree, fuel properties, and energy efficiency of the torrefaction process. The independent parallel reaction (IPR) model and particle swarm optimization (PSO) analysis are also adopted for sludge pyrolysis kinetics calculation. The results show that microwave torrefaction is efficient for sludge dewatering with a short duration. The produced sludge solid biofuel is similar to stone-like coal, and can be used for civil or industrial boilers after flotation or just co-firing with briquette. The ash content of sludge solid biofuel shows a declining trend and the surface characteristics change from smooth to rough and fluffy with increasing the torrefaction severity. The bio-oil is mainly composed of phenols, siloxanes, and cholesterol. In addition, hydrogen is detected in the torgas. Furthermore, it is found that lower torrefaction power with a shorter duration yields a higher energy efficiency of the torrefaction process. [Display omitted] • Sludge dewatering and solid biofuel production are implemented simultaneously. • Sludge biofuel obtained by microwave torrefaction is similar to stone-like coal. • Hydrogen is produced from the sludge dewatering process. • Phenols, siloxanes, and cholesterol are the main components of bio-oil. • Short torrefaction duration possesses better energy efficiency. [ABSTRACT FROM AUTHOR]