With the development of information processing technology, 2-D DCT has been used more and more widely. But the 2-D DCT is accomplished by computing twice 1-D DCT successively, and cannot embody the total space characteristic of 2-D transform well. To overcome such drawbacks, the paper has broken the traditional thinking of DCT operation, and proposed 2-D SDCT operation method. First, some new 2-D matrix operation principles are defined. Then, the transform basic matrix used for 2-D SDCT operation was build and the operation principle of 2-D SDCT is described in detail. Finally, the performance of 2-D SDCT was described systematically. The theoretical analysis shows that the proposed method makes 2-D DCT succinct to express, easy to comprehend and convenient to operate.