Abstract: A small, low-cost sensor for detecting atomic oxygen(AO) environment and its effects has been developed in Beijing Institute of Spacecraft Environment Engineering (BISEE) as a part of flight experiment techniques for AO environment and its effects. The sensor is based on an electrical resistance film made of conductive materials susceptible to AO. The AO-resistance osmium film is prepared by plating, UV-light etching and metal etching micro processing. It can be used to measure the flux and fluence of AO, with an operating life of about 1 year in the altitude of 400?500 km. The AO effect sensor is made of a quartz plate sputtered with silver film and coated on it a test film. It can be used to determine the AO erosion rate of the test film.