The generation of a flat supercontinuum (SC) spectrum of over 100 nm in the 1.55 μm region by injecting 1.6 ps, 10-GHz repetition rate optical pulses into an 80-m-long dispersion-flattened highly nonlinear microstructure fiber (HNL-MF) is demonstrated. The experimental microstructure fiber with a nonlinearity of ～11 W-1·km-1 has small normal dispersion and is characterized by flattened chromatic dispersion. The chromatic dispersion is about -0.58 ps·nm-1·km-1 at 1550 nm, and it varies less than 1.5 ps·nm-1·km-1 between 1500 and 1650 nm. The generated flat broadband supercontinuum ranging from 1503 to 1593 nm has the flatness of ±2.5 dB. This flat broadband supercontinuum can simultaneously supply more than 1100 multi-wavelength channels with 10-GHz spacing. The multi-wavelength pulse trains at 10 Gbit/s based on spectral slicing are also demonstrated. Such supercontinuum source has important applications, such as wavelength division multiplexing optical communication system and optical wavelength convertor.