Due to the special strategy role and the trends of global warming, the Arctic region attracts many interests. The underwater acoustics play a very important role in the ocean research work of Arctic region and its neighborhood. The research work of underwater signal processing in polar region is relative late than the other field of underwater acoustics. It focuses on polar region especially the Arctic ocean environment, studies the effects of underwater acoustic environment and its adaptive signal processing methods. In this paper, the outline of research work, since WWII, of underwater acoustics in Arctic region and its neighborhood is introduced. The specific research issues and results different from the traditional underwater acoustics in this special region are discussed. It is shown that the characteristics of Arctic ocean environment has more important role in underwater signal processing and sonar design, some special treatments must be taken in matching the requirement of Arctic underwater acoustics.