Projection temporal logic(PTL) is an extension of interval temporal logic(ITL) with a new projection operator prj and infinite intervals which has been well investigated in the past ten years.In this paper,we review the work on PTL in four aspects:(1) decidability,complexity and expressiveness of propositional PTL(PPTL);(2) modeling,simulation and verification language(MSVL);(3) formal verification approaches with MSVL and PPTL;and(4) supporting toolkit MSV.