Abstract: This application discloses a video decoding method, a video encoding method, and related apparatuses. The method includes: determining a current video frame; obtaining, from video frames that have been decoded, a first quantity and a second quantity in a target reference frame associated with the current video frame; the first quantity being a quantity of intra-frame decoded blocks in the target reference frame, and the second quantity being a quantity of inter-frame decoded blocks in the target reference frame; determining, according to a relationship between the first quantity and the second quantity, a target resolution used for decoding the current video frame; and decoding the current video frame by using the target resolution. In this application, the technical problem of the relatively low video encoding and decoding efficiency caused by complex processing operations in the related art is resolved.