Abstract: Proposed, on the basis of correction of the theoretic formula for calculation of cooling time of the hot-rolled steel tube, is an empirical formula which is used for the same purpose, and can produce data that is further close to the measured values.The said formula is then verified.Furthermore, statistics is made for the cooling times of hot tubes of several types as being cooled down from 850℃ to 100℃.The statistic result proves that the cooling time as calculated with the empirical formula is rather close to the measured data.