A microwave-assisted synthetic method to form a series of AC/TiO2 for application as photocatalytic degradation of formaldehyde (HCHO) is presented. The influence of prepared conditions such as microwave power, microwave time, and the ratio of activated carbon and titanium dioxide sol (AC/TiO2-sel) on the degradation of HCHO was investigated. HCHO conversion of 58.68% was achieved by AC/TiO2 at microwave power of 700W for 15 min with AC/TiO2-sel ratio of 1 : 2, which maintained multiple properties including high content of anatase and TiO2 largely distributed on AC without reunion, and possessed abundant functional groups for degradation. The influence of operation parameters on the degradation was also investigated: increasing dosage of catalyst and decreasing the initial concentration of HCHO could increase the conversion of HCHO. Acidic conditions can promote degradation effect. Stronger intensity of UV irradiating could improve efficiency of photocatalytic conversion of HCHO.