A bit rate allocation method for video coding and a bit rate allocation method for code units are applied to a client or a server. The method includes: obtaining a target bit rate and a coded bit rate of a current frame; determining a frame uncoded bit rate based on the target bit rate and the coded bit rate; obtaining current code unit prediction costs and frame uncoded unit prediction costs that are determined based on precoding; and determining a target bit rate of a current to-be-coded code unit based on the frame uncoded bit rate and a cost ratio, the cost ratio being a ratio of the current code unit prediction costs to the frame uncoded unit prediction costs.