Exploring implicit logic and influencing factors of job selection and quitting of rural social workers will benefit human resource building of rural social workers in China and provide reference for social work to help rural vitalization. Drawing on the theory of field and Alain Touraine’s illustration on the concept of subject， a case study of 21 rural social workers finds the motivations for being social workers fall into three categories：for living， for career development and for altruism and reflection. In general， rural social workers have realistic demands for survival and life, but also desire to gain a sense of meaning and become creative and even altruistic subjects. The industry， institution， government or policy and rural communities in the occupational field of rural social work not only have their special features， some of their advantages help to shape the subject of rural social workers； but there are also many limitations similar to those of urban social work, which push the social workers to quit their jobs. Future policy should not only promote occupational welfare but also increase opportunities of self-realization for rural social workers. Scales to measure social workers’ willingness to transform society， practice altruism and reflect on mainstream values should be developed and applied to future related studies.