The morphology of InP self-organized islands grown on GaInP buffer layer was calculated by employing the combination of the elastic energy Err cause d by the stress of the buffer layer and the excessive surface energy of the island Ess. The result shows that the island morphology is affected by the mi smatch between GaxxIn1-x1-xP buffer layer and InP island. With Ga content in creasing in GaInP layer, the island elongates itself with mismatch increasing. T he island metamorphosis was elongated also with volume increasing of the island. The parameters of the buffer layer determine the volume of the island which is at the minimized state. The morphology of different InP/GaxxIn1-x1-x P systems, grown on GaAs substrate by metal organic chemical vapor deposition me thod, was consistent with our calculations.