It is a basic method to establish Internet of Things(IoT) by interconnecting all existing physical applications. However, there has not yet been an effective architecture to guide horizontal interconnections of physical applications. To address the problem, this paper proposes a Physical Model Driven software Architecture for Internet of Things (PMDA), which supports the horizontal interconnections of physical applications. PMDA is composed of three models, namely, Physical Model, Sense-Execute Model and Application Model. The connections and interactions between models, and interactions among components in the models are realized by connectors, which satisfies some certain constraints. The composition of the three models in PMDA and the interactions among the models are formally described by an Architecture Description Language named Wright. The effectiveness of horizontal interconnections of physical applications based on PMDA is verified by PAT, in terms of deadlock-free,divergence-free and nonterminating. Besides that, those properties of IoT application systems developed under guidance of PMDA are proven by mathematical induction.