The invention provides a method for producing influenza viruses in large scale by using a bioreactor, which comprises the following steps of: (1) inoculating passage cell suspension into a vector tank, and setting the parameters of the bioreactor to perform a cell adsorption and culture process, wherein a serum culture medium is used in the cell adsorption and culture process; (2) when cells are grown to proper density, rinsing the cells to remove serum components, inoculating influenza virus liquid into the vector tank, and setting the parameters of the bioreactor to perform a virus adsorption and propagation process, wherein a serum-free culture medium containing TPCK (tosyl-L-phenylalanine chloromethyl ketone) pancreatin is used in the virus adsorption and propagation process; and (3) harvesting the virus liquid. The method has the advantage that: the high-titer virus liquid can be obtained by adopting the tide type bioreactor and using the passage cells for propagating the influenza viruses. The method overcomes the defects of the traditional transfer bottle culture and other bioreactors, and can continuously produce high-titer viruses in large scale.