Interannual change of summer temperature in Qingdao was analyzed based on the monthly average temperature data during June and August in 1951—2010 by using the method of principal component analysis and cluster analysis through SAS software.According to principal component analysis, the first principal component was the summary of summer temperature departure in Qingdao.The positive(negative) direction reflected the positive(negative) anomaly of temperature and the strength reflected its degree.The second principal component reflected the temperature difference among each month of the same year.The larger the absolute value of the second principal component was, the greater the temperature difference among each month was.Cluster analysis showed that the change of average monthly temperature in summer in Qingdao could be divided into three categories.The first type was that the temperature was low in June and July and warmed up in August.The second type was that the average temperature in July was the highest while in June and August it was relatively low.The third category was that the temperature in June was low and it got high in both July and August.The year of 1993 and 2003 were of the first type, 2005 of the second type and the other years of the third type.