We review and discuss the methods of efficient frequency convension of broadband Nd:glass laser and its significance and difficulties. Firstly, we present the existing methods such as angular spectral dispersion, chirp-adapted phase-matching, multicrystal quadrature, and retracing point phase-matching in detail. Also we discuss their properties and limitations. On this basis, we propose a simple and efficient broadband frequency tripling scheme by mixing a narrowband pulse and a broadband one in the sum-frequency process. We study the conversion bandwidth numerically and discuss the physical cause of its high conversion bandwidth. The application prospect of this scheme on high power laser device is discussed as well.