Based on the experimental results of strength developments of mass concrete using low-heat portland cement, rational correction of proportioning strength were investigated. The strength of concrete curing under low temperature was less than that of standard curing specimen in the same maturity. Therefore in case that concrete in structure is cured under low temperature, correction value of concrete strength for proportioning is necessary to be determined adequately. The influence of high temperature curing in an early age on the strength development of concrete was not recognized because reaching the maximum temperature of concrete took much time.