The invention relates to the technical field of well drilling wellhead equipment in oil industries, in particular to a two-stage casing head. The two-stage casing head comprises an outer cylinder, a first-stage hanging cylinder, a switch control cylinder, a positioning shear nail, a two-stage hanger and a slip; the outer cylinder is internally provided with the first-stage hanging cylinder, a first annular groove is formed in the inner side of the upper portion of the outer cylinder, a first annular table which can seat into the first annular groove is arranged on the outer side of the upper portion of the first-stage hanging cylinder, and the lower portion of the first-stage hanging cylinder is mounted on the inner side of the lower portion of the outer cylinder in a sleeved mode; at least one pressure relief hole is distributed in the position, on the lower portion of the first annular groove, of the outer cylinder, and a valve is mounted on at least one pressure relief hole; and theswitch control cylinder is arranged on the inner side of the first-stage hanging cylinder, and the switch control cylinder and the first-stage hanging cylinder are fixedly mounted together through the positioning shear nail. According to the two-stage casing head, hanging of multiple layers of casings can be achieved, the axial length can be decreased, thus the two-stage casing head has good safety while mounting is convenient, the outer cylinder can be directly connected with a well drilling four-way and a blowout preventer at a wellhead through an existing flange plate, and in the integraloperation process, the four-way and the blowout preventer do not need to be detached.