Faraday rotation induced when electromagnetic wave penetrates through ionosphere is the major source for the cross polarization in observed Stokes brightness temperature with a polarimetric microwave radiometer. Faraday rotation correction employing TEC (total electron content) data generated by IRI (international reference ionosphere) model can not meet polarization rotation correction accuracy in some low latitude regions. To improve the correction accuracy, the following two methods were used: 1.integrating Faraday rotation angle along observation path and 2.correcting Faraday rotation by using TEC data released by IGS. Analysis results show that the first method is hardly helpful to improve the correction accuracy, while the second one can improve Faraday rotation correction accuracy considerably. By using TEC data, the correction method can satisfy the correction accuracy of polarization rotation angles which a polarimetric microwave radiometer demands.