To analyze the influence of climate change on the frequency of extreme events in Beijing,firstly, Mann-Kendall method is used to deal with annual average temperature data in 1952-2010 of Beijing station. Since abrupt change of the annual average temperature of Beijing was not successfully detected,BFAST is introduced to deal with the monthly average temperature time series,this is because monthly average data is more sophisticated compared with annual average data,diasaster or extreme events can be better reflected on monthly data. The article further explores the changes of the frequency of extreme high temperature events in Beijing after gaining the trend and abrupt change of monthly average data. The results show that the climate change trend and abrupt change which BFAST detected is consistent with the change of the frequency of extreme high temperature events. BFAST is a powerful tool to determine climate change and to analyze climate extremes.