An encoding includes: obtaining, by an encoder, data to be encoded, where the data to be encoded is at least one LCU; determining, a quantization depth parameter of the LCU according to a preset bit rate control algorithm, and adding the quantization depth parameter into the data to be encoded; determining, a QP of each CU according to a size of a minimum picture block and a size of each CU included in the LCU; calculating, by the encoder, a QP difference of each CU according to the QP of each CU and a QP prediction value of each CU; for each CU that satisfies a preset condition, carrying, by the encoder, the QP difference of the CU in the CU; and encoding, by the encoder, the quantization depth parameter, the QP difference of the CU that satisfies the preset condition, and each CU to obtain a bit stream.