With the increasing scarcity of spectrum resources， the increasing severity of radio regulations， and the increasing fierceness of electromagnetic warfare， the research of the electromagnetic spectrum situational has to transit from spectrum perception to spectrum cognition. This paper reviews the current research status of the theories and methods for spectrum situational cognition from four aspects： The mathematical models and fundamental mechanisms for a multi-layer spectrum situational cognition system， the extraction and fusion of cross-region multi-dimensional electromagnetic features， the efficient completion and prediction for spectrum situation， and the precise inference and intention judgment for spectrum-related behaviors. To address the complex multi-domain multi-dimensional electromagnetic spectrum environment and diversified tasks， it is critical to develop a framework of spectrum situational cognition from “data to semantics” “semantics to behaviors” “a single region to cross regions” “a single layer to multi layers”. This framework builds up foundations， both theoretically and technically， for efficient spectrum sharing in space-terrestrial integrated information networks， efficient radio regulations， and advantages in the electromagnetic spectrum warfare.