Poterovich在T^* S^2上構造了一個單調拉格朗日環面,Albers和Frauenfelder接著證明了這個環面是不可置換的(non-displaceable)。我們利用類似的構造方式在T^* RP^2上造了一個單調拉格朗日環面,並提出一些觀察,試著解釋這個環面是不可置換的可能性。Leonid Poterovich constructed a Lagrangian torus in T^* S^2 and then Albers and Frauenfelder proved that Lagrangian torus is non-displaceable. We use similar construction to construct a monotone Lagrangian torus in T^* RP^2. Moreover, we provide some observations explaining this monotone Lagrangian torus would be non-displaceable.