The advantages and disadvantages of several secondary development methods of AutoCAD platform are compared, and ObjectARX 2018 based on C ++ language is selected to realize the input and browse of attribute informations for ancient trees in AutoCAD 2018. The attribute informations of ancient trees could be input by users through human-computer interaction, and the informations are stored in the extended attribute XData of the graph.Add a reactor to AutoCAD to obtain the drawing object of mouse position and its XData, and then the attribute informations are displayed in the Tooltip. The logic structure of the program is introduced, and the key codes are provided, which could be used as a reference for similar functions.