Underground space excavating and constructing method

The invention provides an underground space excavating and constructing method. The method comprises the steps that an original well and a receiving well are constructed on two sides of proposed underground space, the proposed underground space is divided into multiple channels arranged alternately, and each channel is arranged from the original well to the receiving well in a penetrated mode; by means of a pipe-jacking method, pipe joints are arranged in each channel, soil bodies between adjacent side plates of the pipe joints of the adjacent channels are removed, the adjacent channels are communicated with one another, top plates of the pipe joints of the adjacent channels are connected through metal plates, and supporting units used for supporting the pipe joints are arranged in the channels; reinforced concrete is poured on the top plates and bottom plates of the pipe joints, and the reinforced concrete is poured on the side plates of the pipe joints of the channels on two sides of the underground space. Relocation of existing equipment on the ground is avoided or reduced, influence on the existing equipment and the surrounding environment by the underground space construction is reduced; the construction method is simple, the construction cost is low, the construction quality is high, and the construction efficiency is fast.