Disclosed is a UPS isolation control high speed transfer switch for switching a power supply path of a UPS to a bypass line and a power supply system equipped with the high speed transfer switch. The switch is isolated from the UPS and detects the output power of UPS, and switches a power supply path from a normal power line to the bypass line, by turning off the transfer switch of the bypass line after turning off an output breaker of a normal power line when the output power is deviated from a preset normal range. Furthermore, the switch performs a switching to the bypass line only when the output breaker of the UPS is actually turned off, after confirming the turn-off of the output breaker when switching the power supply path to the bypass line.