The invention, which mainly relates to processing on a caption special effect in the broadcast television program manufacturing and broadcasting fields, discloses a method and system for square object mode transformation of a two-dimensional caption. The method comprises: (1), obtaining basic dimension parameters of an original caption window and basic scale parameters; (2), dividing the window into an even number of basic units according to the basic dimension parameters of the original caption window and obtaining basic scale parameters based on the basic parameters of the caption window; (3), numbering the basic caption windows and formulating a transformation task execution sequence of all the basic caption window based on a task order; and (4), collecting a pixel point position based on a determined fixed value of each window basic unit and obtaining a new pixel point position based on the determined fixed value parameters and a transformation function f (x, y, t). Moreover, the system consists of an original information collection unit, a window dividing unit, and a rendering assignment unit; according to basic scale parameters of an original caption window, the original information collection unit and the window dividing unit divide the window into an even number of basic units; according to the basic parameters of the caption window, basic scale parameters are obtained; and the rendering assignment unit carries out assignment. According to the invention, basic information collection of a caption window enables transformation parameters to be dynamically extracted; and division of the caption window enables coordinated displaying of different caption window units to be realized, thereby realizing a caption transformation effect.