Nonlinear polarization rotation (NPR) mode-locked lasers have attracted numerous attention due to their compact structure and high reliability. Based on this mold locking principle, an ytterbium-doped fiber femtosecond laser was designed and built. When the bidirectional pumping power reached 380 mW, the laser was mode-locked with a fundamental frequency repetition rate of 22.8 MHz. The output pulse was centered at 1030 nm with 224 fs for the pulse duration, 180 mW for the average power, 8 nJ for pulse energy, and 40 nm for the bandwidth at 10 dB. The beam had a good quality with signal-to-noise ratio greater than 50 dB. The laser can realize self-start mode locking with a ring laser structure. Besides, the third order passive harmonic mode locking with 68.5 MHz for the repeat frequency was observed by increasing the pump power to 1.6 W. Due to the advantages of line width, pulse width and pulse energy, the laser has application significance in spectral measurement, Raman imaging and other fields.