The invention discloses a glass substrate smelting furnace which comprises a smelting furnace body (5). The smelting furnace body extends forwards to form a pre-smelting pond (1). Two feed inlets (2) are symmetrically formed in a front breast wall of the pre-smelting pond. A left breast wall and a right breast wall are each provided with a burning lance (3), and a smoke outlet (4) is further formed in the upper portion of the front breast wall. The pre-smelting pond is additionally arranged on the front side of the smelting furnace body, batch can be pre-smelted at high temperature firstly through the burning lances, and heated and pre-smelted liquid glass flows into a smelting pond of the smelting furnace body and only needs little energy to obviously improve smelting quality; meanwhile, the feed inlets are formed in the front breast wall of the pre-smelting pond, temperature influences of a material pile formed by the accumulated batch on the smelting furnace body can be reduced or even eliminated, and the material pile only fluctuates in the pre-smelting pond and does not affect the temperature of the smelting pond of the smelting furnace body. Process stability is guaranteed, and a good foundation is provided for product quality.