The invention discloses a field portable carbonization furnace for in-situ resource utilization of agricultural waste and graded preparation of biochar. The field portable carbonization furnace comprises a cover, a furnace body, a material inlet, a smoke exhaust pipe, a stainless steel outer layer, a carbonization area, a heat insulation layer, a heating partition plate, an airflow limiting sliding cover, a ventilation opening, a feeding opening, three or more heat conduction pipes, a heating area, a condensation pipe, a waste gas collection chamber, a one-way ventilation valve, a tail gas guide pipe and one or more sieve meshes. According to the invention, the product disclosed by the invention has the characteristics of mobility, portability, simple operability and the like, is suitablefor being used in special environments such as fields, mountainous regions and the like, and particularly has outstanding functions aiming at the generation of a large amount of waste agricultural biochar after autumn harvest; and the carbonization furnace disclosed by the invention is reliable and safe in charcoal preparation process, high in preparation efficiency, low in cost, small in occupiedarea and portable, and can meet the requirement of field in-situ preparation of charcoal.