The present invention discloses a manufacturing method of glass fibre reinforced cement flue. A partition plate is made on the moulding plate by use of cement mortar, and then a base plate and two side-plates are prefabricated on the moulding plate. After the two side-plates are turned up, the partition plate is placed between both side-plates, and then an upper moulding plate is placed. Finally top plate is prefabricated. Further, said prefabricated plates are cured with moulds unti their strength is 70% of designed strength and the moulding plates can be removed. After it is continuously cured to their designed strength, a finished product can be obtained. In the cement mortar the short-cut glass fibre may be mixed, or firstly a layer of cement mortar is poured, then a layer of glass fibre network fabric is laid, and further a layer of cement mortar is poured again to form two-mortar-one-net or multi-mortar-multi-net structure.