Abstract: In order to make full use of the image data of engineering drawings,the design goals,functions and characteristics as well as new techniques of TH-DAIMS 3.0 are introduced.In TH-DAIMS 3.0,the adaptive local thresholding to raise the ability for removing the blue background and noise of blueprints,the connecting area classification to classify graphs and characters,the pattern matching technology for recognizing the dimension characters,the oct-direction connecting area search and contour tracing for extracting curve from drawing image,the interactive classification vecterization to vecterize drawings and the bidirection raster and vector mixed design to increase the speed of interactive design are used.At the end of the paper,the applications of THDAIMS in design department,construction department and archive department are addressed.