Abstract: A special interpolation of the element displacement field using the displacement along each side of element is proposed and a new C₁ conforming quadrilateral thin plate bending element is developed. With the special interpolating method, the completeness conditions and the C₁ conforming conditions of element are separated. C₁ conformity and completeness of the element are proved theoretically. Numerical examples show that the element has more advantage than non-conforming elements.