I have performed systematic studies in the area of mid-to-high latitude climate system variation and climate prediction. The innovative results can be summarized as follows: (1) We have studied the variation and impact of the climate system over mid-to-high latitudes: revealing the decadal change of the summer North Atlantic Oscillation and the possible mechanism, and revealing the impact of summer North Atlantic Oscillation on the Northern Hemispheric summer climate; revealing the physical processes of the impact of the Antarctic Oscillation on monsoons, and proposing the mechanism of the tropical bridge; revealing new features of the East Asian climate extremes and the possible influential factors over mid-to-high latitudes. (2) We have studied the predictability of the mid-to-high latitude climate systems and developed the prediction methods: proposing a new theme to improve the dynamical prediction of the Arctic Oscillation and revealing a new predictor for the prediction of the Pacific Decadal Oscillation; developing some new prediction models, which have clear physical basis and can significantly improve the regional and global climate prediction. I have published and been accepted 62 papers (22 as the first author) in peer-reviewed scientific journals, 42 (16 as the first author) of which have been or will be published in SCI journals. I was given the National Natural Science Awards of China (second class) in 2014. All the published papers have been cited 429/228 (362/238 by other researchers) times in SCI/CSCD journals.