The invention relates to a ventilation system and a ventilation method for tunnel construction. The system consists of a wind turbine, an air exhaust vertical shaft, a jet flow tee joint, an exhaust duct, a filter connection tee joint, a fresh air duct, a tee joint purification foundation, a separation air duct, a fan, and a fresh air filter; a ventilation vertical shaft is constructed outside a tunnel before construction, and during construction, air feeding is adopted on an upper part, and exhausted air on a lower part is directly filtered and removed; a fresh air machine can drive fresh air and exhausted air synchronously, wind energy is fully utilized, and energy is saved and emission is reduced; and the system can be industrially designed, and produced in the standardized, generalized and serialized mode, can be widely applied to tunnel construction industry, mining industry, dust operation industry and other industry, and belongs to the field of tunnel construction and ventilation and purification.