The spatial distribution and time evolution of long wave in Northern China in spring and summer were calculated by Empirical Orthogonal Function (EOF) and harmonic wave analyses to daily data from the National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis for 1958-2008. The results showed that: (1)  In spring, a complete wave lies from Aral Sea to Japan, that is to say, there is a ridge acting mostly from Lake Balkhash to Lop Nur and a trough in Northeast China, both of ridge and trough enhanced. In summer, there is a ridge in Ural Mountain and the  Okhotsk Sea, and a trough in Lake Baikal, the trough acting mostly from Mongolia to North China, however, the trough weakened in the past 51 years. (2) The long wave departure has an anti-correlation relationship between Northwest China and North China and their upper and lower regions in spring, and in summer, the center of long wave departure moves toward east comparing with the spring.

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