A picture prediction method, comprising: determining motion vectors of W control points in a current picture block; obtaining, by means of calculation, motion vectors of P pixel units of the current picture block by using a motion model and the motion vectors of the W control points, wherein precision of the determined motion vectors of the W control points is 1/n of pixel precision, precision of the motion vector that is obtained by means of calculation and that is of each of the P pixel units is 1/N of the pixel precision, the P pixel units are some or all of pixel units of the current picture block, the motion vector of each of the P pixel units is used to determine a corresponding reference pixel unit, in a reference picture, of a corresponding pixel unit, W, n, and N are integers greater than 1, N is greater than n, and P is a positive integer; determining the corresponding reference pixel unit according to the motion vector of each of the P pixel units; and performing interpolation filtering on a pixel of the corresponding reference pixel unit, in the reference picture, of each of the P pixel units by using an interpolation filter with a phase of Q, to obtain a predicted pixel value of each of the P pixel units, wherein Q is an integer greater than n, N=16, and Q is equal to N; wherein W is equal to 2 and the motion model is represented as follows: { ν Nx = ν 1 x − ν 0 x × N L x − ν 1 y − ν 0 y × N L y + Nν 0 x / n ν Ny = ν 1 y − ν 0 y × N L x + ν 1 x − ν 0 x × N L y + Nν 0 y / n; or { ν Nx = ν 1 x − ν 0 x × N / n L x − ν 1 y − ν 0 y × N / n L y + N / n ν 0 x ν Ny = ν 1 y − ν 0 y × N / n L x + ν 1 x − ν 0 x × N / n L y + N / n ν 0 y, wherein L represents a width or a height of the current picture block, ( v 0 x, v 0 y) and ( v 1x,v 1y) represent motion vectors, whose precision is 1/n of the pixel precision, of two control points, v Nx represents a horizontal component of a motion vector, whose precision is 1/N of the pixel precision, of a pixel unit with coordinates of (x, y) in the current picture block, and v Ny represents a vertical component of the motion vector, whose precision is 1/N of the pixel precision, of the pixel unit with the coordinates of (x, y) in the current picture block. determining motion vectors of W control points in a current picture block; obtaining, by means of calculation, motion vectors of P pixel units of the current picture block by using a motion model and the motion vectors of the W control points, wherein precision of the determined motion vectors of the W control points is 1/n of pixel precision, precision of the motion vector that is obtained by means of calculation and that is of each of the P pixel units is 1/N of the pixel precision, the P pixel units are some or all of pixel units of the current picture block, the motion vector of each of the P pixel units is used to determine a corresponding reference pixel unit, in a reference picture, of a corresponding pixel unit, W, n, and N are integers greater than 1, N is greater than n, and P is a positive integer; determining the corresponding reference pixel unit according to the motion vector of each of the P pixel units; and performing interpolation filtering on a pixel of the corresponding reference pixel unit, in the reference picture, of each of the P pixel units by using an interpolation filter with a phase of Q, to obtain a predicted pixel value of each of the P pixel units, wherein Q is an integer greater than n, N=16, and Q is equal to N; wherein W is equal to 2 and the motion model is represented as follows: { ν Nx = ν 1 x − ν 0 x × N L x − ν 1 y − ν 0 y × N L y + Nν 0 x / n ν Ny = ν 1 y − ν 0 y × N L x + ν 1 x − ν 0 x × N L y + Nν 0 y / n; or { ν Nx = ν 1 x − ν 0 x × N / n L x − ν 1 y − ν 0 y × N / n L y + N / n ν 0 x ν Ny = ν 1 y − ν 0 y × N / n L x + ν 1 x − ν 0 x × N / n L y + N / n ν 0 y, wherein L represents a width or a height of the current picture block, ( v 0 x, v 0 y) and ( v 1x,v 1y) represent motion vectors, whose precision is 1/n of the pixel precision, of two control points, v Nx represents a horizontal component of a motion vector, whose precision is 1/N of the pixel precision, of a pixel unit with coordinates of (x, y) in the current picture block, and v Ny represents a vertical component of the motion vector, whose precision is 1/N of the pixel precision, of the pixel unit with the coordinates of (x, y) in the current picture block.