  In this paper polarized valon distribution is derived from unpolarized valon
distribution. In driving polarized valon distribution some unknown parameters
exist which must be determined by fitting to experimental data. Here we have
used Bernstein polynomial method to fit QCD predictions for the moments of
$g_1^p$ structure function, to suitably the constructed appropriate average
quantities of the E143 and SMC experimental data. After calculating polarized
valon distributions and all parton distributions in a valon, polarized parton
density in a proton are available. The results are used to evaluate the spin
components of proton. It turns out that the results of polarized structure
function are in good agreement with all available experimental data on
$g_{1}^p$ of proton.
