The invention relates to the technical field of circular accelerator random cooling, and more particularly to a broadband phase equalizer for a random cooling system. The broadband phase equalizer includes a broadband quadrature hybrid network. A signal is input from the Port A of the broadband quadrature hybrid network, and is divided into two signals which have equal amplitude and a phase difference of 90 degrees and which reach the port C and port D of the broadband quadrature hybrid network. The two signals are reflected from the port C and port D reflection, wherein one signal is reflected to the port A to form signals which have the same amplitude and inverted phases (phase difference of 180 degrees), and which are offset; the other signal is reflected to the port B of the broadband quadrature hybrid network. The port B of the broadband quadrature hybrid network is connected with an adjustable delay line. The port C and the port D of the broadband quadrature hybrid network are connected to terminal open-circuit or short-circuit coaxial lines through coaxial connectors respectively. The broadband phase equalizer has a very wide bandwidth, corrects the phase in a plurality of octave frequency bands, achieves a phase equalizing purpose, simple in circuit, easy to assemble and debug, easy to control and operate, and good in repeatability.