The invention discloses an N - 1 + 1 fast calculation method of a distribution network based on power supply path search. The method mainly comprises steps of searching all power supply paths and recording the power supply mapping relation between all power-supplying equipment and power-supplied equipment on the power supply paths, recording the correspondence relationship between all boundary switches and the power-supplied equipment, and obtaining the complex electric-mapping relation between the power-supplying equipment and the boundary switches according to the relation between the power-supplying equipment and the power-supplied equipment and the relation between the boundary switches and the power-supplied equipment, etc. The method can quickly determine the operable boundary switches in the event of power supply equipment failure, and has the advantages of fast calculation speed, short time and high efficiency.