A chemical preparation method of diameter and length controllable metal nano conducting wire can be operated on different matrixes, such as mica, glass, ceramics and plastics, etc. and includes the following steps: soaking the scanning probe microscope base mica or glass plate in the octadecyl mercaptan saturated solution of ethyl cyanogen, taking out and drying in the air for stand-by; placing the scanning probe tip in air plasma, discharging and making hybrophilic treatment for stand-by; directly dipping the scanning probe tip into the oxidant and cutting the wire on the above-mentioned base to form metal wire, drying in the air and soaking the base in reducting agent solution, taking out the base, washing with clear water so as to obtain the invented metal nano conducting wire.