A method of separating text and graphs in digital image data is used to separate digital image data into graph data and text data. According to a default separating parameter, the digital image data are partitioned into several operating matrices. One then sets a default crossing reference level for comparison analyses to compare adjacent pixel units in each operating matrix. When the digital characteristic value of a pixel unit is greater than the default crossing reference level and the digital characteristic value of its one adjacent pixel unit are smaller the default crossing reference level, the operating matrix is given a weight. Afterwards, all the weights are added up to give a weighted statistical value, which eventually is used to separate the graph data from the text data.