As embedded systems are widely applied, their requirements are becoming increasingly complex, making requirements analysis a critical stage in embedded system development. How to correctly describe and model requirements has become a primary issue. This study systematically investigates the current requirements descriptions of embedded systems and conducts a comprehensive comparative analysis to deepen the understanding of the core concerns of embedded system requirements. The study first applies the systematic literature review method to identify, retrieve, summarize, and analyze the relevant literature published between January 1979 and November 2023. Through the automatic retrieval and snowball processes, 150 papers closely related to the topic are finally selected for the comprehensiveness of the review. The study analyzes the existing capabilities of embedded requirements description languages from their description concerns, description contents, requirements analysis elements, etc. Finally, it summarizes the challenges to the current requirements descriptions. Moreover, aiming at the task of intelligent synthesis of embedded software, it puts forward the need for the expressive ability of embedded system requirement description languages.