Video encoding method and system

The invention provides a video encoding method and system. The video encoding method comprises the following steps: dividing a transposed matrix of a DCT coefficient matrix into a plurality of parts according to columns; carrying out partial DCT on a video data matrix by using the part of the transposed matrix and the DCT coefficient matrix for each part of the transposed matrix to obtain a transformation matrix; carrying out quantification, inverse quantization and IDCT on the transformation matrix to obtain an inversely-transformed matrix; adding the inversely-transformed matrix by a previous video rebuilt matrix obtained for the former part of the transposed matrix to obtain a current video rebuilt matrix so as to obtain a video rebuilt matrix. According to the method and the system for encoding video, the partial DCT is started to be carried out on the next part of the transposed matrix during carrying out quantification, inverse quantization and IDCT on the part of the transformation matrix. The method can be used for implementing flow line operation, optimizing the area of a video encoding circuit and improving the performance of a video encoding rebuilt circuit.