Abstract: The Nobel Prize in Physics in 2021 was awarded to the German scholar Klaus Hasselmann and two other scientists. Klaus Hasselmann is a famous oceanographer, meteorologist, climatologist and physicist. This paper will briefly describe Hasselmann’s research career and introduce his important academic achievements in the aspects of signal-to-noise ratio in atmospheric response and multi-pattern fingerprint method of climate change attribution. Combining with the state-of-the-art conclusions about climate change attribution in the latest Sixth Assessment Report of the Intergovernmental Panel on Climate Change, this paper expounds the theory and methodology of climate change attribution based on Hasselmann’s pioneering work, which constitutes one of the important scientific bases for addressing climate change.