Using　the　base　line　forces　as　fundamental　variables　to　describe　the　stress　state　for　two　dimension　problems　and　the　displacement　gradients　that　are　the　conjugate　variables　of　the　base　line　forces,　which　describe　the　deformation　state　of　objects,　a　4-node　plane　element　model　based　on　complementary　energy　principle　is　proposed.　In　this　paper,　the　complementary　energy　of　an　element　is　constructed　by　using　the　base　line　forces.　The　equilibrium　conditions　are　released　by　the　Lagrange　multiplier　method,　and　a　modified　complementary　energy　principle　described　by　the　base　line　forces　is　obtained.　The　formulation　of　the　4-node　plane　element　is　derived　by　assuming　that　the　stress　is　uniformly　distributed　on　each　face　of　a　plane　element.　A　finite　element　procedure　of　complementary　energy　principle　is　developed　using　MATLAB　language.　The　numerical　results　of　examples　show　that　this　model　has　high　precision　and　is　free　from　mesh　sensitivity.