The invention provides a flexible traction angle branching type linkage linear three-plane projection demonstration board, which is composed of a projection board, a projection connection line mechanism, a linear projection mechanism and a linkage mechanism; the projection connection line mechanism driven by a soft rope is adopted, so that a connection line of a front surface projection and a horizontal projection of a linear movable point is vertical to an X axis, and the front surface projection and a side surface projection of the linear movable point are vertical to a Z axis; the retractable linear projection mechanism is adopted, so that a projection length of a straight line can be changed and situations of various positions of a space straight line are met; the linkage mechanism is adopted, so that the distance from the horizontal projection of the same point to the X axis is equal to the distance projected to the Z axis from a side surface. In a utilization process, three projection caps of the movable point are unscrewed by hands, two projections of the movable point are sequentially moved to appointed positions, and then the corresponding projection caps are screwed; a third projection can be linked to an accurate position, and the corresponding projection cap is screwed. Seven unchanged teaching aids are replaced with a dynamical and changeable real-object teaching aids, and a dynamic demonstration effect is remarkably improved.