The experimental study of the Yb³⁺-doped figure-of-eight cavity fiber laser using the nonlinear amplifying loop mirror (NALM) was reported,which was pumped by 976 nm semiconductor laser. The fiber laser can generate 0.2 mW average power of 43.6 ps pulse duration at a repetition of 18.2 MHz,and operating central wavelength was 1053.3 nm,spectrum width was 8 nm,though grating pairs to compensate the positive dispersion outside the cavity,as short as 616 fs output pulse was obtained after amplifying,which was to our knowledge the shortest pulse to date from this kind of Yb³⁺-doped fiber laser.