To explore the ventilation optimization and energy saving issues in the construction of multiple working faces in extra-long highway tunnels, the air volumes required for a single working face under drilling and blasting construction conditions and TBM tunneling conditions were determined respectively based on theoretical calculations. Combined with the tunnel construction organization scheme, two ventilation schemes were proposed, and they were compared and selected according to the configured power of axial fans. Based on the recommended scheme, the layout scheme of pollutant-discharging jet fans was designed, and its feasibility was finally verified by on-site measurements of pollutant concentrations. The research shows that the air volumes required for the working faces of the drilling and blasting method and the TBM method are 1 980 m³/min and 1 500 m³/min, respectively, which are both controlled by the minimum allowable air velocity in the tunnel. The total fan power of the alternating construction scheme for multiple working faces is only 39% of that of the conventional construction scheme, which significantly reduces energy consumption. On-site measurements indicate that the alternating construction scheme for multiple working faces can meet the requirements of air velocity and oxygen content during the construction period. The average mass concentrations of CO, SO₂, PM_2.5, and PM₁₀ are lower than the allowable values specified in the Technical Specifications for Construction of Highway Tunnel (JTG/T 3660—2020), indicating that the scheme is highly feasible. However, short-term pollutant accumulation occurs in local areas during excavation blasting, requiring an appropriate increase in air supply. The research results effectively guide the construction ventilation of Tianshan Shengli Tunnel and can provide a reference for similar projects.