Polarized Parton Distributions in the Valon Model

We calculated the polarized parton distributions in leading order approximation in QCD from valon model. Polarized structure function of the nucleon are analyzed in the polarized valon model in which a nucleon is assumed to be a bound state of three polarized valence quark cluster(valons). It is shown that the results of the model calculation agree rather well with the SMC and available experimental data . Our results for ${\mathrm{\Gamma }}_1$ of hadron and deuteron are in good agreement with experimental data for some value of $Q^2$.