The invention discloses a slope reinforcement device for environmental-friendly building municipal engineering. The slope reinforcement device comprises a hollow long straight cylinder body; outside threads are formed in the outer wall of the cylinder body; a bearing is fixed at the upper part of the inner wall of the cylinder body; a guide rod is installed on an inner ring of the bearing in an interference fit manner; the guide rod and the cylinder body are in a same axis; the lower side of the guide rod is provided with a spiral part and a threaded part sequentially from top to bottom; gear inserted bars are installed on the two sides of the cylinder body respectively; each gear inserted bar is composed of a gear end and an inserted bar end which are connected to each other; each gear end is rotationally installed on the cylinder body through a rotary shaft; and in addition, a part of each gear end is arranged in the cylinder body and is meshed with the spiral part of the guide rod. According to the slope reinforcement device, the structure design is reasonable, and the stability is improved with combination of the unfolded gear inserted bars and concrete mortar in a drill hole.