In order to promote the recycling and utilization of construction waste, the dry mixed mortar was prepared by replacing part of cement with regenerated micropowder, and the effects of the fineness, content and compounding ratio of the regenerated micropowder on the consistency, compressive strength, flexural strength and microstructure of the mortar were explored. The results show that the consistency of mortar decreases with the decrease of regenerated micropowder particle fineness, the compressive strength and flexural strength of mortar at 28 d increase, and the strength reaches the maximum value after grinding for 40 h. With the increase of the content of regenerated micropowder, the consistency of mortar shows a downward trend, and the compressive strength and flexural strength of mortar at 28 d show a trend of increase first and then decrease. When the content of regenerated micropowder is 10% (mass fraction), the compressive strength reaches the maximum value. With the increase of the compounding ratio (mass ratio) of regenerated micropowder, the consistency of mortar shows a downward trend, and the compressive strength and flexural strength of mortar show a trend of increase first and then decrease. When the compounding ratio of micropowder milled for 20 h to unmilled micropowder is 6∶4, its compressive strength reaches the maximum value.