Carbon nanotube film (CNTF) with two-dimensional CNT network structure is adopted to prepare CNTF/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) thermoelectric composites, which overcomes the disadvantages of low content, easy aggregation, and random orientation of CNTs when dispersed in polymer. A vacuum-assisted filtration method was proposed, which can uniformly and sufficiently penetrate the polymer into CNTF along thickness direction for fabrication of CNTF/PEDOT:PSS composites. A highest electrical conductivity of 806.2 S/cm at 300 K was achieved for the composites with 60 wt% PEDOT:PSS loading, which was 51.0% higher than that of the original CNTF (534.1 S/cm). A maximum power factor of 339.6 μW·m⁻¹·K⁻² at 320 K was achieved with a corresponding Seebeck coefficient of 67.7 μV/K. This study provides a universal method for fabrication of other kinds of CNTF/conductive polymer thermoelectric composites.