The molecular weight and molecular weight distribution greatly affect the properties of a polymer Classical polymer weight determination methods involve typically indirect methods, such as gel permeation chromatography(GPC), and light scattering .However, these methods are time-consuming and can not provide absolute molecular weight .MALDI/TOF has the ability to directly measure absolute molecular weight of polymer and molecular weight distribution. Besides average molecular weight, MALDI-TOF can provide information about the repeat unit and end group of the polymer. We analyzed several synthetic polymers by MALDI/TOF .Their average molecular weights were calculated and their molecular structures were proposed.