Homogeneity of the climate data is p recondition on studying climate change. This paper used SNTH technique to test the homogeneity of climate series of Lanzhou meteorlogical station, and the inhomogeneity test on meteorological factors such as p recip itation, average temperature, maximum temperature, minimum temperature, average wind speed and sunshine hourswas conducted; meanwhile, the reason was analyzed based on the station history files and metadata information. The results show that inhomogeneity existed in time series of p recip itation, average temperature, maximum temperature, minimum temperature and sunshine hours, and the main reasons were relocation of station, changes of instruments, changes in statistic methods and urban heat island effect.