A method for forming a semiconductor structure includes: providing a substrate, a sacrificial layer and active layer on sacrificial layer being formed on the substrate; etching the active layer and sacrificial layer up to a surface of the substrate to form a plurality of active lines arranged in parallel and extending along first direction; filling an opening located between two adjacent ones of active lines to form a first isolating layer; etching an end of active lines to form an opening hole; removing sacrificial layer along opening hole, to form a gap between a bottom of the active lines and substrate; filling a conductive material in the gap to form a bit line extending along first direction; patterning the active lines to form a plurality of separate active pillars arrayed along first direction and second direction; and forming semiconductor pillars on top surfaces of respective ones of the active pillars.