The invention discloses a cement rebar biogas digester and a manufacturing device and method thereof. The cement rebar biogas digester comprises a cement shell, a hydraulic pressure feeding pipe and a hydraulic pressure discharging pipe, wherein the cement shell is composed of two hemispherical cement shell bodies which are matched with each other, a rebar net frame is embedded in each hemispherical cement shell body, an outward extending joint edge is arranged at the joint of the two hemispherical cement shell bodies, and a binding material and glue-woven net cloth are attached to the joint edge of the two hemispherical cement shell bodies; an air duct is arranged at the top end of the upper hemispherical cement shell body, the hydraulic pressure discharging pipe and the hydraulic pressure feeding pipe are both arranged at the top end of the upper hemispherical cement shell body, a hydraulic pressure discharging pond is connected to the top end of the hydraulic pressure discharging pipe, and a hydraulic pressure feeding pond is connected to the upper end of the hydraulic pressure feeding pipe. The cement shell is manufactured with a die firstly, and then hole digging is conducted for sealed installation. The biogas digester is high in structural strength, long in service life, high in sealing performance, short in construction period, low in manufacturing cost, and firm in sealing, and raw materials are cheap and easy to obtain.