An actively mode-locked femtosecond pulse fiber laser with coorse wavelength division multiplexing (CWDM) as the filter was successfully achieved. When the laser was pumped at 186 mW, the mode-locked pulses centered at 1550 nm with 10.2 nm bandwidth (corresponding to 247 fs pulse width) was obtained at the repetition rate of 2.5 GHz. The average output power of the laser was 1.3 mW.