Social tourism, which was started in Europe,is a potentially valuable solution for tourism/holidays participation of the social disadvantaged populations, solving social exclusion and promoting social integration, and improving social well-being etc. Western research in the field of social tourism began in the middle of 20th century, covering the origins of social tourism, concepts, operation mechanism, values and evaluation, as well as the practices in countries. Compared with this, Chinese scholars are rarely involved in this field, and even social tourism is still a fairly new concept in China. In view of this, this article tries to have an overall review of the English literatures on social tourism in the West. Firstly, the paper generalizes the origin of the term 'social tourism' and some viewpoints on the beginning of social tourism; furthermore, the characteristics of social tourism are concluded, including socialization, public non-profit, and intervention etc. Secondly, this paper comprehensively and exhaustively reviews and analyses the main research topics of social tourism in the West, such as: 1) the concepts and definitions of social tourism. Since there still has been no general concept up to now, this research classifies the existing concepts into three types based on different perspectives of definers: definitions of demand perspective, definitions of supply perspective, definitions of both demand and supply perspective; 2) the operation mechanism of social tourism, namely, 'who are the interveners', 'who are the beneficiaries' and 'how to intervene'; 3) explanation of the reasons for the development of social tourism from the perspectives of tourism rights and ethics respectively; 4) how to evaluate the values and effects of social tourism; 5) the development models of social tourism in different countries.