Abstract: To solve the semilinear elliptic problem, the triangular quadratic finite elements and interpolated coefficient finite elements are discussed. Superconvergence O( h⁴)at each vertex and side midpoint is proved, which is similar to that of classical finite elements. These facts are also shown by numerical examples.

Key words: Semilinear elliptic problems, Triangular quadratic finite element, Interpolated Coefficient, Superconvergence