A large-mode-area double-cladding Yb-doped photonic crystal fiber (PCF) mode-locked laser based on semiconductor saturable absorber mirror (SESAM) is reported. Without any pulse compression mechanism, a pulse with duration of 3.3 ps and repetition frequency of 93.33 MHz is generated in a ring cavity when the power coupling into the fiber reaches 12.2 W. The central wavelength and the spectrum bandwidth are 1027 nm and 1 nm, respectively. When the power coupling into the fiber reaches 14 W, a maximam output power of 150 mW can be achieved. The laser can work stably for 2 h. Q-switched and pulse splitting are observed and analyzed.