The embodiment of the invention claims a processing method for transforming data, comprising: estimating and analyzing the numerical value range of the image data after two transformations based on pre-setting two needed transforming matrixes needed by two transformations; estimating the characteristic different value of numerical value of two transformations based on two transformed numerical value; applying the first transformation of two transformations to the data to be transformed, and compensating the data after the first transformation based on the different value of estimated numerical value. The embodiment of this invention further discloses a processing device for transforming data, method and device of coding and decoding. Appling the embodiment of this invention, which can adjust the numerical value of the transformed data so as to enable the numerical values of the image data to be the same after different transformation and really reflect the influence of the transformation to the data when applying the self-adoptive block transformation technique, and to select the transformation with better effect and improve the coding efficiency.