Voucher system is one of the basic forms of public service provision, and medical vouchers is a specific application of the voucher system in the field of healthcare services. As a regional policy innovation practice in the field of social security in the Greater Bay Area, cross-border medical vouchers have transformed from pilot programs to regular programs after years of development. Compared to the domestic voucher system, the cross-border characteristics of cross-border medical vouchers, especially based on the context of one country, two systems, provides a new perspectives and development for the comprehensive and implement of the voucher system. Through a horizontal comparison with other market-based public service vouchers and an analysis of the intrinsic characteristics of healthcare services, the operational mechanism of cross-border medical vouchers lies in the construction of a system design centered on the essential attribute of welfare, with consumers redeeming the services as the core. The way to realize the welfare is to improve the accessibility of healthcare services. The method of improving accessibility should be combined with the intrinsic mechanism of vouchers to facilitate consumers to complete the consuming-selection process, strengthen administrative regulation, and alleviate the asymmetric Information of consumer information as an entry point.