The invention relates to a detachable steel tube section construction method used for freezing method construction in a tunnel contact channel. According to the method, apart from common tunnel segment parts 3, non-detachable parts 1 and detachable parts 2 are further adopted. The detachable parts 2 are arranged in the tunnel contact channel, the non-detachable parts 1 are arranged in the peripheries of the detachable parts 2, the detachable parts 2 are connected with the common tunnel segment parts 3 through the non-detachable parts 1, and accordingly, a whole detachable steel tube section is formed, wherein each non-detachable part 1 is sequentially provided with three layers, namely, a thin steel plate outer layer, a flexible transition layer and a steel structure segment inter layer from outside to inside. The construction method comprises the following steps that the detachable steel tube section is mounted according to the description; freezing holes and pressure released holes are constructed; the freezing method construction is carried out to form a freezing curtain; and the detachable parts 2 are dissembled, and contact channel construction through a mining method is carried out.