Abstract: The realization of high resolution algorithm has been paid more attention in recent years. This paper gives the model of wide-band beam-space direction finding problem and studies the Root-MUSIC algorithm. The roots in the unit circle of the beam-space Root-MUSIC are divided into two parts, one is corresponding to the true direction, and the other is not related to the source direction. Sub-array model is used here to form beams to focus the root corresponding to the true direction in a reduced order polynomial. This process reduced the computation burden. Simulation results in various beams have shown that the beams with wider main-band and lower side-band have better estimation and resolution performance, and proved the effectiveness of the wide-band beam-space reduced order Root-MUSIC.