ZnO thin films prepared by using quantitative filter paper as a template and Zn(CH3CO2) 2·2H2O ethanol precursor solution were characterized by scanning electron microscopy(SEM) and X-ray diffraction(XRD) . The effects of sample calcination temperature,precursor concentration and filter paper types were studied,and the growth process was investigated by infra-red(IR) spectroscopy and thermogravimetric analysis/differential thermal analysis(TGA/DTA) . The results show that samples soaked in a 1.5 mol/L Zn(CH3CO2) 2·2H2O ethanol solution and calcined at 600 °C yield ZnO films of uniform particle size,approx-imately 30,40 and 50 nm,for fast-,medium-and slow-speed filter papers,respectively. The formaldehyde gas sensing properties of the ZnO nanoparticles were tested,showing that the material prepared from fast-speed filter paper has a higher response to 120-205 ppm formaldehyde at 400 °C than that prepared from medium-or slow-speed paper,which depends on the particle size. ZnO thin films prepared by using quantitative filter paper as a template and Zn (CH3CO2) 2.2H2O ethanol precursor solution were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effects of sample calcination temperature, precursor concentration and filter paper types were studied, and the growth process was investigated by infra-red (IR) spectroscopy and thermogravimetric analysis / differential thermal analysis (TGA / DTA). The results show that samples soaked in a 1.5 mol / L Zn 2 · 2H 2 O ethanol solution and calcined at 600 ° C yield ZnO films of uniform particle size, approx-imately 30, 40 and 50 nm for fast-, medium-and slow-speed filter papers, respectively. The formaldehyde gas sensing properties of the ZnO nanoparticles were tested, showing that the material prepared from fast-speed filter paper has a higher response to 120-205 ppm formaldehyde at 400 ° C than that prepared from medium-or slow-speed paper, which depends on the particle size.