A method and a device for coding and decoding images are disclosed. The method for coding images includes: determining a second length according to a direction of a division line, a scale value, and a position parameter value; determining a division mode of the image block according to the direction of the division line, a first length, the second length, and the scale value; coding the image block according to the division mode of the image block; and coding a direction parameter value, the scale value, and the position parameter value. With the technical solution provided in the embodiments of the present invention, the determining of the division mode of the image block on the image coder is simplified.