The portable sugar mill is established on a mobile platform for transport to the harvesting field, so that the juice of the harvested sugar cane may be processed and refined in the field. The portable sugar mill converts the juice, which contains sucrose, into raw sugar crystals (brown sugar) and molasses. The portable sugar mill includes a separator tank, a pre-heating tank, a clarifier, and three successive stages of evaporative crystallization and separation of crystals from syrup. The portable sugar mill has a programmable logic controller and a plurality of sensors, control relays, pumps, motors, heaters, and valves that operate automatically under direction of the programmable logic controller.