<p>Digital twins exhibit two primary characteristics: real-time interaction between the physical and virtual spaces, and integration throughout the product lifecycle. Currently, research on digital twins that addresses the full product lifecycle rather than specific phases is still lacking. To systematically construct digital twins throughout the lifecycle systematically, this paper proposes four research questions that guide the research. Based on the analysis of these research questions, a novel full lifecycle model is proposed in this paper. The subjects, temporal-spatial relationships, and evolution mechanisms of digital twins are proposed, and three types of update channels are discussed to facilitate their evolution. In order to implement the full lifecycle model, some key technologies are introduced for constructing geometric, physical, behavior, and rule models of both physical and virtual entities. Additionally, two cases with different perspectives are used to validate the feasibility of the proposed model. Case 1 presents an overview of the digital twin operation process throughout the full lifecycle of a machine tool. Case 2 focuses on the use &amp; maintenance phase, wherein a fault behavior model of the machine tool is constructed, and a reinforcement learning algorithm is used for fault diagnosis.</p>