A method for monitoring ion implantation, comprising: a), providing a control piece and forming a mask layer; b), performing ion implantation process to implant a predetermined dose of impurity ions into the control piece, an area on the control piece uncovered by the mask layer being an impurity implantation area and an area on the control piece covered by the mask layer being an impurity non-implantation area; c), peeling off the mask layer from the control piece; d), performing oxidation treatment on the control piece; and e), respectively measuring thicknesses of the oxide layers on the impurity implantation area and the impurity non-implantation area of the control piece, and monitoring the impurity dose of the ion implantation on the basis of a ratio of the thickness of the oxide layer in the impurity implantation area to the thickness of the oxide layer in the impurity non-implantation area. By this method, it is possible to accurately monitor whether or not the dose of the implanted ions meets the predetermined requirement, and it is possible to effectively avoid the defects of incorrect monitor result caused by the variation of the intrinsic resistance of the semiconductor, improve the accuracy of the monitoring, and thus improve the performance and yield rate of the device.