Molecular dynamics simulation in coarse-grained model of polyvinyl alcohol is made to get semicrystalline polymer from a molten state with slow cooling and partial crystallization.Evolution of static structure factor shows that intensity increasing in small-angle scattering appears before the Bragg peak in early crystallization,which is consistent with experimental observations with small/wide angle X-ray scattering.Simulated semicrystalline polymer shows a structure resembling Ying-shaped micro-beam model.Different cooling stages have different formation mechanisms with ordered structures.From crystallization to glass temperature in solidification process,stretching of molecular chain and arranging in parallel between straight molecular chains exist.Adjustment of straight chains in relative positions is only allowed by material activate.