The invention provides a stationary bed pressurizing and gasifying device for preparing synthesis gas. The device comprises a stationary bed pressurizing and gasifying unit for providing synthesis gas crude product by using the biomass and randomly selected coal substance as raw material; a condensing and separating unit, which comprises a quenching cleaning unit for removing solid phase entrainment in the synthesis gas crude product, and condensing and separating the empyreumatic oil in the synthesis gas crude product to cause the synthesis gas crude product to crack, hydrogenise and convert, a noncatalytic part oxidation unit capable of converting the main component as carbon monoxide and hydrogen, and a post-processing unit for processing the converted synthesis gas.