This study conducted practical development of 300N/mm2 precast concrete. As a result, the followings were found to be important, lengthen mixing time for fluidity and strength development, sufficiently deforming of the specimen using vibrator, deforming by pressurizing and depressurizing with squeeze-type pump before casting the member, and protecting form direct steam in AC-curing tank. In addition, strength development can be evaluated by effective-age of over 20°C, and the curing patterns that can achieve compressive strength of 300N/mm2 and small shrinkage is to shorten the 90°C steam-curing time and apply 180°C AC-curing over 4 hours or 150°C AC-curing over 12 hours.
