The present invention relates to a guide tool, the said guide tool is capable of assisting one end of a coaxial cable to be coupled to an end connector; it comprises of a body installed with a guide mechanism therein, the said guide mechanism possesses a guide tube for guiding the cable central conductors of different regulations; the said guide tube can move along the direction of the axle line by the elastic element for rapidly and precisely inserting the central conductor and the dielectric into the columnar member of the end connector and further becomes the best auxiliary tool.