Using the precipitation-sol method, nanometer TiO2 particles were prepared with Ti(SO4)2 as precursor in the experiment. Photocatalytic degradation experiments for formaldehyde were carried out with an aim to inspect the influence of preparation conditions of TiO2 on photocatalytic degradation performance. The results show that degradation efficiency of formaldehyde attain 78% in 6 h as the concentration of Ti(SO4)2 0.05 mol/L, hydrohzation temperature 80℃and time 4 h, pH 2 for congregate with 0.10 mol/L KOH, maturation temperature 90-...