Artificial intelligence (AI) has penetrated into many fields. How to construct strategic human resources management practices under the background of AI technology has gained great attentions from many researchers in the world. Consequently, the conception of human resource department's client relationship management (HRDCRM) has been put forward. HRDCRM is a focus topic in the practice areas of strategic human resource management. This paper introduced relational capital as a mediating variable and collected two-wave lagged data (N = 235) from the enterprises located in eastern and southern China to conduct an empirical research on relational capital's mediate role by which HRDCRM influences sustainable enterprise performance. Empirical results reveal that under the control of enterprise's ownership and lifecycle-stage, relational capital plays a partial mediate role in the influence of HRDCRM on sustainable enterprise performance. Therefore, the key to improving sustainable enterprise performance is developing the level of HRDCRM and promoting harmonious development between HRDCRM and relational capital.