How to obtain high strength while remain the good shielding performance of MXene film is a big challenge, which limits its further application. Herein, we report on fabrication of mechanically strong and high-performance EMI shielding Ti3C2Tx composite film by incorporating of poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) and then treatment with concentrated sulfuric acid to remove the insulating PSS. By introducing of 30 wt% PEDOT:PSS into Ti3C2Tx film and with acid post-treatment, the EMI SE of composite film with thickness of ~6.6 μm is up to 40.5 dB while the tensile strength is 38.5 ± 2.9 MPa and the increment in tensile strength is as high as 155% when compared to that of Ti3C2Tx film. It achieves a good balance between shielding performance and mechanical property, which has not been achieved in reported literatures. The combination of mechanical and shielding performances portfolio outperforms the counterpart of other polymer composites filled with MXene.