In 2007, Pillay gave a geometric description for the imaginaries in proper pairs of ACF. Based on this result, we are able to define an totally additive rank which is monotone in algebraic closure. Moreover, we can prove that this rank is monotone under parameter extension and detects forking. In this talk, we will present the construction of the rank together with some examples and give a proof sketch about how does the rank character forking independence. In fact, the proof also gives a practical characterization for forking.