The invention discloses an internal-circulation low temperature grain storage system and method. The internal-circulation low temperature grain storage system comprises a grain bin, ventilation equipment, a grain condition detection unit and an intelligent ventilation unit, wherein at least one ventilation opening is formed in the bottom of the grain bin; an electric window is arranged on one wall surface; an electrically operated valve is arranged at each of the ventilation openings; each of the ventilation openings communicates with one end of a thermal insulation pipe; the other end of each of the thermal insulation pipes is connected with a circulating fan; a ground ventilation cage is arranged on the ground surface in the grain bin; the ventilation equipment comprises at least one centrifugal fan, the at least one circulating fan and at least one air conditioner; the grain condition detection unit comprises a plurality of grain pile temperature sensors and a bin inner temperature and humidity sensor; the intelligent ventilation unit comprises a first server and an intelligent control cabinet; the first server is in communication connection with a small-sized meteorological station outside the bin; and the operation of the ventilation equipment and the opening and closing of the electrically operated valves are automatically controlled by the intelligent control cabinet. According to the internal-circulation low temperature grain storage system and method, the intelligent regulation and control can be carried out timely when the grain pile temperature and the bin inner temperature and humidity deviate from the safe grain storage range, the labor intensity of grain bin keepers is reduced, and the grain bin management cost is greatly reduced.