According to the postcode database, the postcode of Jinnan District, Tianjin is 300350. Among them, the first two digits 30 represent Tianjin; The third digit, 0, indicates Jinnan District in the postal area; The fourth digit 3 represents Jinnan District, Tianjin; The last two digits, 50, indicate the specific delivery area in Jinnan District, Tianjin.