Transparent and conductive ITO thin films were prepared on quartz glasses by the sol-gel dip-coating method. This process is affected by factors such as doping level of tin, number of dip-coatings (layers or thickness of film), withdrawal speed, annealing temperature and time. The effects of each factor at 5 levels on the properties of ITO films has been studied and optimized using the method of orthogonal experiments (L25(5)5). Quantitative analysis of the parameters in the orthogonal array design was performed and the results indicate that when the sheet resistance and transmittance are the two targets, the optimum experimental conditions are: mol ratio of Sn: In: 1/10, number of dip-coatings: 8, withdrawal speed: 200 mm/min, annealing temperature: 550°C and time: 70 minutes. To validate the project, another experiment was performed under the above conditions to determine the best performance of ITO film. The test results show that the sheet resistance is 125Ω/γ and transmittance is 86.2%, which meets the expected aim.