Methanol has been deemed to be a favorable medium for the source of hydrogen because its liquid nature facilitates the storage, transportation, and utilization of hydrogen. Currently, steam reforming is the most common method to generate hydrogen from methanol in chemical industry and hydrogen fuel cell field. However, methanol reforming often involves high temperature and pressure, massive capital investment, as well as undesirable byproducts (CO, CO2, etc.) formation. To overcome these disadvantages, in this work, we describe an in situ assembly and stepwise thermal treatment method to synthesize fibrous AgNPs/g-C3N4 aerogel, which exhibits efficient photocatalysis activity for the splitting of pure methanol at room temperature. Encouragingly, hydrogen is continuously produced while neither CO nor CO2 is found in the products, which could be attributed to the moderate redox feature of silver in the AgNPs/g-C3N4 aerogel. More importantly, this COx-free hydrogen evolution process can prevent the poisoning of catalysts, opening a new opportunity for developing low-carbon chemistry.