The invention provides a flexible traction line tube stretching-type linkage linear three-face projection demonstration board which is composed of a projection panel, a projection ligature mechanism, a linear projection mechanism and a linkage mechanism. A flexible-rope-driven projection ligature mechanism is used, so that the ligature of the front projection and the horizontal projection of a linear dynamic point are perpendicular to an X axis. The front projection and the side projection of the linear dynamic point are vertical to a Z axis. The scalable linear projection mechanism is used, so that the linear projection length is changeable to meet various location situations of a space line. The linkage mechanism is used to ensure that the distance from the horizontal projection of the dynamic point to the X axis is equal to the distance from the side projection of the dynamic point to the Z axis. When the demonstration board is used, three projection caps of the dynamic point are loosened by a hand; after two projections of the dynamic point are successively moved to specified locations, the projection caps are tightened; the third projection of the dynamic point automatically comes to a correct location; and the projection cap is tightened. According to the invention, a dynamically changing physical teaching aid is used to replace seven constant teaching aids, and the dynamic demonstration effect is significantly improved.