Hot air circulation drying system and method

The invention relates to the technical field of drying and discloses a hot air circulation drying system and a hot air circulation drying method. The hot air circulation drying system comprises a heater, a fan and a hot air drying box, which are sequentially arranged, wherein an air inlet pipe is arranged on the heater; an air outlet pipe is arranged on the hot air drying box; an inlet and an outlet are formed in the hot air drying box; a first drying area, a microwave drying area and a second drying area are sequentially arranged in the hot air drying box; a plurality of groups of industrial microwave pipe devices are arranged in the microwave drying area; at least one humidity sensor is arranged on each group of industrial microwave pipe device; the first drying area and the second drying area are communicated with the fan respectively and are communicated with the air outlet pipe respectively; the hot air circulation drying system also comprises a hot air circulation pipe, a hot air circulation device, a f