Recent advances and geological significance of magmatic epidote(MEp) are summaried in this article. MEp stability in magma is firmly correlated with temperature, pressure, fH₂O and fO2. Crystallization sequence from magma of MEp depends on pressure but not fO₂. while,fO₂ can changes MEp minimum cystallization pressure from 5×10⁸ Pa(fO₂=NNO)to 3×108 Pa(fO₂=HM). MEp which crystallized earlier than biotite or hornblende in the magma, can not be used as a barometer, but be useful in caculating the ascent speed of magma. Those MEp that occurred as subsolid mineral with or without resorption of earlier-formed hornblende, can be use as pressure indicator for intrusion. With respect to the influence of fO₂, Granite can be subdivided into Magnetite and Ilmenite series. MEp that occurred in Magnetite series granite indicates the minimum pressure of 3kbar and 5kbar of Ilmenite series granite.