The invention relates to a detection tool in an electric power system, in particular to a phasor analyzer. The analyzer comprises a base and a dial. A central shaft is arranged on the dial. A rotatable current phasor pointer used for indicating the current phasor is installed on the central shaft. Scale lines for representing angles are marked on the disc face of the dial, wherein the 0-degree scale line and 360-degree scale line coincide with each other and are perpendicular to a horizontal line. Line voltage phasors (shown in the description) and phase voltage phasors (shown in the description) which are successively arranged in 120 degrees along the clockwise direction are marked on the disc face of the dial. The phase voltage phasor (shown in the description) points to the 0-degree scale line and the angle between the line voltage phasor (shown in the description) and the leading phase voltage phasor (shown in the description) is 30 degrees. A corresponding reverse phasor is arranged for each line voltage phasor and a corresponding reverse phasor is arranged for each phase voltage phaser. The analyzer is simple to operate and judges precisely, thereby facilitating that an operator finds out the phase voltage to which the current phasor belongs and judges the accuracy of wiring of a current secondary loop by rotating the current phasor pointer, and analysis and determination processes are simplified.