TiO2/AC photocatalyst was prepared by the sol-gel method.The affecting factors on the photocatalytic degradation of formaldehyde wastewater,such as initial pH value of formaldehyde wastewater,illumination time,dosage of TiO2/AC photocatalyst,initial concentration of formaldehyde wastewater,usage times of the photocatalyst,etc.,were investigated by the degradation rate.The experimental results showed that:under the conditions,formaldehyde wastewater’s initial concentration 30mg/L,pH value 13,the dosage of TiO2/AC photocatalyst 4g/L,the illumination time 3h under the irradiation of 40W UV-light,the degradation rate of formaldehyde wastewater was 96.6%;After the TiO2/AC photocatalyst was used repeatedly at the sixth time,the degradation rate of formaldehyde wastewater was over 92%.