Carboxycoumsrins were synthesized via the solid phase synthesis conviently. The resin bound cyclic malonic ester reacted with o-methoxy or o-hydroxybenzaldehydes. Then cyclization was processed under H2SO4 to afford the products in excellent purities and yields. Carboxycoumsrins were synthesized via the solid phase synthesis conviently. The resin bound cyclic malonic ester reacted with o-methoxy or o-hydroxybenzaldehydes. Then cyclization was processed under H2SO4 to afford the products in excellent purities and yields.