Based on the universality of the parton distributions inside valons, parton distributions of pions are investigated and parametrized from the experimentally given parton distributions of proton within the valon model The structure function F2(x) is given at fixed scale Q20 = 1 GeV2. Due to the abundance of the pair numbers of sea quarks at a very small x region, the structure function decreases rapidly for small x to a local minimum. Then from the contribution of the valence quarks, F2(x) increases to a local maximum at x (∽－)0.5.