Over the past two centuries, the research on working fluids drove the tremendous progress of organic Rankine cycle to convert medium- and low-temperature heat into power efficiently. With the increasingly stringent requirements on working fluids, the search for alternative working fluids is a never-ending task. In the present work, a comprehensive review of working fluids selection of ORC is presented to summary the current research results, find out the issues and guide the future developments. The research of working fluid selection is divided into three stages according to research method firstly. Then, the research progress of each stages is summarized. In addition, the research challenges and recommendations for further research of working fluids selection and even for novel thermodynamic cycle are highlighted as well. The results show that for traditional ORC, the optimal working fluid could be selected almost by key parameters such as critical temperature, acentric factor and Jacob number, etc. More importantly, the development direction of novel thermodynamic cycle is presented.