976 nm LD pumped laser is used as the pump source and high concentration Yb3+ -doped fiber is adopted as gain medium.Using the nonlinear polarization rotation (NPR) effect of the fiber,mode-locked pulse is obtained.The center wavelength of the mode-locked pulse is 1046 nm with 3 dB bandwidth of 24 nm。The pulse duration is 54 ps and the average power is 93 mW.In order to achieve a high fundamental repetition rate,we use a shorter cavity.The fundamental repetition rate reaches 41 MHz.