The utility model discloses a broadband silencer for a fan. The broadband silencer comprises an enclosure. An air inlet and an air outlet are formed at the two ends of the enclosure respectively. A tapered flow guide cylinder is arranged at each of the two ends of the enclosure. An inner container straight tube is arranged in the enclosure, and a tapered tube is arranged at each of the two ends of the inner container straight tube. The broadband silencer is characterized in that a solid silencing core is arranged in the inner container straight tube, and the two ends of the solid silencing core are tapered; each tapered flow guide cylinder has a sandwiched structure; a silencing orifice plate and extra-fine glass wool are arranged in each sandwich; and a silencing layer is arranged in the enclosure, and a noise isolation layer is arranged outside the enclosure. By the tapered flow guide cylinders with the sandwiches, airflow state is rational, and a noise reduction effect is greatly improved; the silencing layer is arranged in the enclosure, and the noise isolation layer is arranged outside the enclosure, so that the external radiation of noise in the silencer is greatly attenuation and isolated; and practice shows that more than 38dB(A) of static noise and more than 35dB(A) of dynamic noise can be directly reduced, air flow resistance loss is lower than 260Pa, and the broadband silencer is actually environment-friendly, efficient and energy-saving. The broadband silencer is low in manufacture cost and long in service life, and the noise of low frequency, intermediate frequency and high frequency can be eliminated.