Provided is an expansion pipe two-stage expansion device. For overcoming the shortcoming that an existing reducing expansion head props a conical piece open by lifting and pulling an expansion tip cone and accordingly expansion according to expected size of the reducing expansion head cannot be ensured, the expansion pipe two-stage expansion device consists of an expansion pipe body at the upper portion and an emission chamber at the power portion, wherein the inner diameter of the emission chamber is larger than that of the expansion pipe body. The reducing expansion head and a fixed-diameter expansion head are located in the emission chamber, the reducing expansion head is located under the fixed-diameter expansion head, the maximum outer diameter of the fixed-diameter expansion head is identical to the inner diameter of the emission chamber, a central pipe is coaxially installed in the expansion pipe, and a plug-in assembly, a hydraulic cylinder assembly, a fixed-diameter expansion head assembly, a control mechanism and a reducing expansion head assembly are sequentially installed in an annular cavity between the central pipe and the expansion pipe from top to bottom. The expansion pipe two-stage expansion device has the advantages of being reasonable in structure, facilitating compensation on a casing pipe with large drift diameter at the lower portion through a small sized casing pipe or a well, enabling the inner diameter of the expanded expansion pipe to be round and regular and providing good shaft conditions for following-up construction operation.