The utility model discloses a " 3-1 " pattern of working a telephone switchboard based on modern distribution network of universe urbanization, the wiring pattern that all has 1 line group of 1-2 contact point formation including 3 times 10kV cable run, every time 10kV cable run, every time 10kV cable run constitutes by 3-4 trunk looped netowrk units, every time 10kV cable run all is connected with other cable run through 1-2 interconnection switch. The utility model discloses be applicable to more that load density is higher, the region of circuit corridor difficulty, single time 10kV cable run's maximum load rate is higher than the line load rate in monocycle net and the wiring of dicyclo net, and the highest power supply of 1 line group load can regard as transition wiring pattern between monocycle net and the dicyclo net, further works a telephone switchboard the pattern to monocycle net, dicyclo net and passes through.