A video image decoding method, wherein the method comprises: determining a motion vector group and a motion model transmission vector of a current decoding block according to a bitstream, wherein the motion vector group comprises at least one motion vector of the current decoding block, and the motion model transmission vector comprises at least four components; determining prediction values of a first component set of a motion model initialization vector of the current decoding block according to the at least one motion vector of the motion vector group, wherein the motion model initialization vector comprises at least four components; and determining a motion model optimization vector of the current decoding block according to the prediction values of the first component set and the motion model transmission vector, so as to decode the current decoding block according to the motion model optimization vector, wherein the method further comprises: determining a motion model quantization precision of the current decoding block; quantizing the motion model optimization vector according to the motion model quantization precision; and decoding the current decoding block according to a quantized motion model optimization vector, as well as determining the motion model quantization precision according to a size of the current decoding block and precision information, characterized in that the size of the current decoding block comprises a width of the current decoding block and a height of the current decoding block, and the precision information comprises a quantization precision of the motion vector group; and correspondingly, the determining the motion model quantization precision according to a size of the current decoding block and precision information comprises: determining the motion model quantization precision Q according to the following formula: Q = 1 / S × P, S = max W H wherein P is the quantization precision of the motion vector group, W is the width of the current decoding block, and H is the height of the current decoding block. determining a motion vector group and a motion model transmission vector of a current decoding block according to a bitstream, wherein the motion vector group comprises at least one motion vector of the current decoding block, and the motion model transmission vector comprises at least four components; determining prediction values of a first component set of a motion model initialization vector of the current decoding block according to the at least one motion vector of the motion vector group, wherein the motion model initialization vector comprises at least four components; and determining a motion model optimization vector of the current decoding block according to the prediction values of the first component set and the motion model transmission vector, so as to decode the current decoding block according to the motion model optimization vector, wherein the method further comprises: determining a motion model quantization precision of the current decoding block; quantizing the motion model optimization vector according to the motion model quantization precision; and decoding the current decoding block according to a quantized motion model optimization vector, as well as determining the motion model quantization precision according to a size of the current decoding block and precision information, characterized in that the size of the current decoding block comprises a width of the current decoding block and a height of the current decoding block, and the precision information comprises a quantization precision of the motion vector group; and correspondingly, the determining the motion model quantization precision according to a size of the current decoding block and precision information comprises: determining the motion model quantization precision Q according to the following formula: Q = 1 / S × P, S = max W H wherein P is the quantization precision of the motion vector group, W is the width of the current decoding block, and H is the height of the current decoding block. determining a motion model quantization precision of the current decoding block; quantizing the motion model optimization vector according to the motion model quantization precision; and decoding the current decoding block according to a quantized motion model optimization vector, as well as determining the motion model quantization precision according to a size of the current decoding block and precision information, characterized in that the size of the current decoding block comprises a width of the current decoding block and a height of the current decoding block, and the precision information comprises a quantization precision of the motion vector group; and correspondingly, the determining the motion model quantization precision according to a size of the current decoding block and precision information comprises: determining the motion model quantization precision Q according to the following formula: Q = 1 / S × P, S = max W H wherein P is the quantization precision of the motion vector group, W is the width of the current decoding block, and H is the height of the current decoding block.