Abstract: A given kind of silica substrates, which low hydroxy group is contained by, was made (quantitative analysis) by the way of infrared differential spectroscopy. Some characteristic absorption peaks of methylene and methyl were measured as a measurement of organic compound. As many data before and after fine CO2 jet spray cleaning were obtained, some rules appeared statistically. Cleaning rate connects to the polluted degree. The higher the polluted degree is, the faster the cleaning rate is. Cleaning rate can also be reduced by the mixture of mineral and big particles. Furthermore, topography affects cleaning rate, too. All of them support the research method, and the process and results claim that for research and production process optimization, it is very important to find a way to insure the consistency of polluted degree on the surface before fine CO2 jet spray cleaning.