The utility model discloses an electrical quantity collecting, testing and analyzing instrument of a power system, which relates to an electrical testing and analyzing instrument which has a plurality of channels, is not commonly grounded, is highly isolated, collects synchronously at high speed, has adjustable recording time and adjustable sampling efficiency and is applicable to all voltage classes of the power supply, and a method thereof. The instrument is a collecting, testing and analyzing instrument which collects at high speed, automatically records and stores, and displays the transient electrical quantity. The instrument can synchronously record the transient wave form simultaneously, automatically or manually records the transient wave form of the electrical quantity, and calculates the over voltage, the surge, the harmonic wave and the like of various transient wave forms. The collection frequency and the recording time are adjustable. The device adopts an embedded operation system and a TCP/IP standard communication protocol, can realize remote control and the synchronous control of the same instrument, and is applicable to the complicated test environments of the power system. The electrical quantity collecting, testing and analyzing instrument of the power system can measure the steady and the transient electrical quantity under a plurality of working conditions, analyze and process the data, and has wide purposes in the debugging, the operation and the scientific research of the power system.