The blurred boundaries, temporary absence of regulation, and dynamic changes in the roles and interactions of members in the emerging field have led to the difficulty for actors with complementary resources in the field to form a clear perception of the "advanced" value proposition of platform enterprises, challenging the original logic of value co-creation within the platform ecosystem based on the premise of the comprehensible value proposition. In this vein, how platform enterprises promote the value co-creation in the context of emerging field has become an important theme that needs to be clarified in practice and theoretical research. Through the comparative analysis of two case companies, i.e., Weiyi and Xinye, this paper identifies two major value co-creation dilemmas in the platform ecosystem in the emerging field context, namely "ambiguous co-creation goals" and "ambiguous co-creation modes", which impede the complementors ' initiative to co-creating value in the focal platform ecosystem. Based on this, we further refines the strategic paths for platform enterprises to stimulate value co-creation of complementors in this context - the "traction" model with the core of explaining value proposition and the "boost" model with the core of co-creating value proposition. The identity positioning of platform enterprises as "leader of the ecosystem" or "partner of other complementors" is the core motive of their strategic actions. Overall, the theoretical model of "co-creation dilemma—identity position—strategic actions" is built, which is the driving mechanism of value co-creation in the platform ecosystem. Based on the characteristics of the emerging field, this paper proposes a strategic path for platform enterprises to promote ecological value co-creation under the premise of participants within the ecosystem have ambiguous perceptions of platform value proposition, and contributes to the research on value co-creation in platform ecosystems.