The invention discloses a small-diameter micro static-pressure steel pipe pile post-grouting construction method. The method comprises the specific procedures of small-diameter steel pipe pile manufacturing, pile pressing, steel pipe inner wall cleaning, gravity grouting, pressure grouting, static curing and concrete casting. In the micro static-pressure steel pipe pile post-grouting construction method, firstly, a small-diameter steel pipe is pressed into a soil layer; after the inner wall of the steel pipe is cleaned by using the water pressure, a finish-rolled thread reinforcement is put into the steel pipe pile, and grouting is performed, so that the small-diameter steel pipe is low in pile pressing resistance and pile body stress, is not obvious in soil extrusion effect, guarantees the perpendicularity, and is high in construction efficiency and low in comprehensive cost; and in addition, as the finish-rolled thread reinforcement is additionally arranged in the steel pipe, on the one hand, the drawing resistance of the reinforcement is used, and on the other hand, subsequent connection with a foundation is convenient. Meanwhile, a staging post-grouting method is adopted to improve a mixing effect between cement paste and soil around a pile foundation so as to prominently improve the bearing performance.