The invention relates to a high fault tolerance coupling transmission mechanism with a guiding function. A coupling interface has certain rotary taper, a plurality of key grooves are circumferentiallyformed along the convex conical surface of a coupling shaft I on one side of a convex cone a floating block is arranged in a coupling shaft II on one side of a concave cone, the outer side of the floating block is coupled with the coupling shaft II, so that the floating block can slide along the axial direction of the coupling shaft II, and the inner side of the floating block is a concave conical surface matched with the convex conical surface, keys in one-to-one correspondence to the key grooves are distributed along the circumferential face of the concave conical surface, and a spring is mounted between the bottom side of the floating block and the inner wall of the coupling shaft II; when the coupling shaft I is inserted into the floating block, the matched convex conical surface andconcave conical surface guide the two coupling shafts to be coaxial gradually and compress the spring simultaneously, and when the two coupling shafts rotate relatively, the keys under the action of the pressure of the spring are pressed into the key grooves so as to transfer a torque stably; when the keys and the key grooves are matched, certain gaps exist to guarantee that the torque can be transferred when a certain included angle exists between the two coupling shafts. The high fault tolerance coupling transmission mechanism provided by the invention is high in fault tolerance, has the guiding function, and is good in stability and convenient to disassemble and assemble.