Abstract: The times and total duration of unplanned outages of thermal power units with the capacity of 100 MW grade and above in 2013 are counted and analyzed. The total times of unplanned outages of all the units are 920, and the total duration of unplanned outages is 53 443.5 hours. The times of unplanned outages caused by boilers and the boiler auxiliary equipment are more than 500, while the ones caused by turbine systems are more than 150. Through the analysis on the reasons for the unplanned outages caused by the boiler and turbine systems, the relative weak deficient parts that affect the unit reliabilities are figured out, which can provide the reference and basis for improving the routine maintenance and management of those deficient parts with poor reliabilities.