This study focus on the application of BIM in intelligent operation and maintenance and uses a hospital as case study.An intelligent building operation and maintenance system is developed based on the BIM and big data. By using the mechanized learning method like fault tree analysis and bayesian probability, the system is able to predict the broken equipment and the fault rate of each element, and meanwhile, to send alerts at the first time for the evidence of quick decisions.In the apps on the mobile ends, the mixed reality technology is introduced for a quickly locating of the fault equipments, which provides troubleshooting ordering based on probability of failure.