[Purpose/significance] With the diversification of mobile search scenarios, cross-app behavior in mobile search has gradually become a topic of concern in information retrieval. There is still less research on the relevant be? havior theoretical model in the existing studies. By drawing on the current results and from the perspective of multi-di? mensional situational elements, this paper constructs a mobile search cross-app behavior theoretical model in order to provide reference for the relevant research. [Method/process] This paper mainly carries out the research through liter? ature investigation and combines the research framework with the existing research.[Result/conclusion] This paper proposed a context-based model of cross-app behavior in mobile search, which described user behavior from four con? textual dimensions: search behavior, search platform, user elements, and environmental elements. It also discusses the practical research design based on this theoretical model, discusses the application value to improve users' cross-app experience in mobile search, and puts forward the design idea of a cross-app behavior prediction system.