Dogs have been domesticated by humans for more than 15,000 years. Now, dogs are the most closely related animals to humans in the world. Behind this evolutional process, the rare ability of dog's social cognition and to read human emotions and situations have been pointed out. The superior cognitive ability of dogs have achieved a unique niche in the human society, also nowadays its cognitive and learning ability has become a valuable research topic in the research field of animal psychology. Recent studies of human and dog suggest that these two species have been developed in the convergent evolution, on the process of domestication. So our best friend “dog” is not just domesticated animals, a “companion” who live together within human society as a unique species. This paper introduces some specific social skills of dogs and its biological properties, which have been revealed by molecular biological and cognitive science approaches in recent years.