Abstract: Although GPC online viscometer, as a kind of GPC equipped with a concentration detector and a viscometer, has been used widely as its brief manner, its results of molecular number, molecular weight and dispersibility retain a lot of errors with the problems of the data applied method and the precision of instrument. The researches indicate that some manners as selecting appropriate band addition, improving the precision of the universal calibration curve, changing the standards injecting method and selecting the proper integrator point can obviously improve on the precisions of molecular number, molecular weight and dispersibility.