Abstract: With the improvement of spacecraft in reliability and life, the in-flight contamination detection becomes more and more important. The influence of space atomic oxygen(AO) on the quartz crystal microbalance may be used for molecular contamination detection, therefore, the properties of quartz wafer after 1×10²⁰ cm^-2 AO irradiation are studied theoretically and experimentally in this paper. The test results show that the sample wafers retain their functions as contamination sensors and the ability for frequency output, despite slight changes in their oscillation frequency and electrical properties.