P-T-t trajectory (P-T-tpath) is a process in which P-T conditions change with time (t) during metamorphism (Miyajiro, 1994). This concept was first put forward by England & Richardson (1977+0977) in a paper on the influence of denudation on the regional metamorphism and evolution of orogenic belts, and was originally called P-T path. The concept of P-T-t trajectory is a major breakthrough in the theoretical study of metamorphism, which makes people re-examine some important issues and basic concepts in the field of metamorphic rock petrology from a dynamic perspective. It marks that the study of metamorphism has entered the geodynamic stage.

The relationship between thermal simulation of metamorphic terrane and P-T-t trajectory, thermal evolution and tectonic evolution experienced by metamorphic rocks shows that the characteristics of actual P-T-t trajectory experienced by rocks are closely related to metamorphic tectonic environment. Taking the continental collision orogenic belt as an example, the relationship between P-T-t trajectory and tectonic-thermal evolution process and related basic concepts are introduced.