A simple dispersion-compensation-free high power mode-locked femtosecond fiber laser with free output coupler is demonstrated. A segment of ytterbium(Yb)-doped double cladding large-mode-area photonic crystal fiber is explored as gain media of the laser. One end-face of the fiber is polished to 0° providing 4% feedback serves as a cavity mirror and a free output coupler. Stable mode-locking is obtained by using a high modulation semiconductor saturable absorber mirror(SESAM). The laser system generates 2.5 W,2 ps,44 nJ pulses that can be dechirped to 430 fs duration outside the cavity.