The present invention relates to a method for preparing a supported metallocene catalyst, and a method for preparing polyolefin using the same, in which the supported metallocene catalyst prepared from the simple process according to the method for preparing the supported metallocene catalyst of the present invention can apply to the polymerization of the polyolefin that is polymerized at low pressure or high pressure; the molecular weight distribution of polyolefin prepared can be easily controlled; and there are effects such that its catalyst activity is significantly higher than that of the existed supported metallocene catalyst, and the molecular weight distribution can be easily controlled.