The service continuity mechanism is to provide multimedia application with seamless multimedia experience over multiple networks (Wifi, 3G, Wimax, LTE) as well as multiple devices (mobile, PCs, PDA, Settop box) in ubiquitous network. However, most of the proposed approaches of service continuity are either not adaptive resources provisioning or based on a specific definition of context in ubiquitous network environment. This paper presents a multi-device service continuity with adaptive resources provisioning mechanism under ubiquitous network relying on IMS which helps perform service continuity according to user's contexts (such as preferences and habits), network context, service context and device context. The contribution of this paper is to propose: 1) service continuity scenario, architecture and requirements; 2) signaling flow of resource switching for the proposed scenario is proposed; 3) process of adaptive resources provisioning is put forward. Evaluation results show that the service continuity approach based on context-aware, multi-device coordination and adaptive resources provisioning process outperforms the traditional service continuity.