A glass manufacturing device includes a main body defining a working space, a fixing device and a grit blower in communication with the working space. The fixing device includes a first fixing assembly, a second fixing assembly, and a locking assembly. The first and second fixing assemblies are rotatably connected with each other and used for clamping a glass substrate. The first fixing assembly includes a number of shielding elements spaced from each other. The locking assembly is used for locking the first and second fixing assemblies. The grit blower is disposed opposite to the first fixing assembly and used for blasting grit on the glass substrate, and thus the portions of the glass substrate which are not shielded by the shielding elements are cut off during the process of grit-blasting. Remaining portions of the glass substrate shielded by the shielding elements are the desired product.