PurposeWith the increasingly intensifying competition and the development and maturity of the modern organization, employees have no longer fully been attached to the organization. The employee‐organization relationship gets more and more attention. As spokespersons of their organizations, the leaders in all levels, to a considerable extent, have an effect on the understanding of the employee for the organization. The purpose of this paper is to explore leader and member exchange (LMX) relationships' impact on employees' organizational commitment and discuss the mediating effect of perceived organizational support (POS) during the period.Design/methodology/approachA sample consisting of 423 employees in four organizations was investigated. After testing the reliability of all questionnaires, the authors constructed a model of the mediating effect of POS between LMX relationships' impact on employees' organizational commitment and used structural equation model technology to verify it.FindingsThe results showed that: affect, loyalty and professional respect have a significant impact on affective commitment but the result of the contribution is not significant. So, work exchange (contribution) was different from social exchange (affect, loyalty and professional respect) in the influence on employee's organizational affective commitment. POS had an intermediary effect between the affect exchange and affective commitment in the organization. Leader‐membership has an important implication for the employee‐organization relationship. The exchanges of different dimensions between the leader and the member were different no matter for the affected contents of the attitude to the organization of the employee or for the affecting mechanism.Research limitations/implicationsAll variable data came from the same employee questionnaires, which may lead to potential problems of same source bias or common method variance. In order to test the influence of common method variance, this research carried out Harman's one‐factor test.Practical implicationsThe organization should emphasize developing the relationship between the leaders from various levels and the members, and in particular the social exchange out of the work must not be neglected.Originality/valueThe present study explores LMX's influence on employees' affective commitment towards the organization from a social exchange perspective. The authors adopted multi‐dimensions LMX, which is different from prior studies (e.g. Wayne et al. and Zhou and Bao) to discuss the mechanism of LMX's impact on subordinates' attitudes to the organization.