Migrant workers in China tend to suffer from inferior status and hardship in the workplace. Domestic private enterprises have become highly market-oriented and have been criticized for exploiting workers; however, some of them have started to pay increasing attention to motivating and retaining workers. The well-being of migrant workers is worthy of study. This study collected survey data from migrant workers in two Chinese private enterprises in the cosmetics industry, aiming to probe how a harmonious and supportive working environment may benefit workers. It is argued that HR???s assistance to line managers can be conveyed to workers via supervisors, leading to perceptions of a supportive working system (represented by the behaviour of HR, managers and supervisors). This kind of system is likely to promote employees??? identification with the organisation and social exchanges with organisational members. Further, these may improve workers??? psychological state and cooperative worker relations. This thesis starts by presenting migrant workers??? experience and discussing how HRM is practised in Chinese private enterprises. Studies of organisational support are introduced as a foundation to explore the influences of HR on employee outcomes???emotional exhaustion and co-worker assistance???through the mechanism of supervisor support. The results validate the substantial role of effective HR assistance to line managers and the role of the supportive supervisor in improving employees??? well-being and in facilitating helping behaviour among co-workers. Finally, implications for management practices and future research are considered.