The cross-wavelet transform method is adopted to study the multi-time scale correlations between the winter temperature,the summer precipitation in Northwest China and the Arctic Oscillation Index(AOI) over the same period,in order to investigate the relationships between climate change in Northwest China,the AOI,and the Eurasian zonal circulation index in recent 56 years.Results show that there are multi-time scale periodic variations in AOI,the temperature and precipitation in Northwest China with significant syntonic periods of qausi-3 a between AOI and the precipitation,while the multi-time scale correlations between AOI and the temperature are quasi-2 a,3—5 a and about 8—11 a with the strongest coherency in 8—11 a syntonic period.The influence of AO on temperature is more remarkable than that on precipitation in Northwest China for the interaction of their interdecadal variation.When the AO is in positive phase in winter,the Eurasian zonal circulation is stronger,and the temperature is higher.The fact that variation of summer precipitation in Northwest China is close related to the prior abnormal AOI is an important factor for the prediction of summer precipitation.