The generation conditions and influence parameters of self-mode-locked pulses in fiber lasers are theoretically studied. By establishing the simulation model of a self-mode-locked erbium-doped fiber laser (EDFL) with a high-concentration erbium-doped fiber-based saturable absorber (SA), the effect of gain saturation energy, orientation angles of the polarizer and analyzer with respect to the fast axis of the fiber, laser coupling output ratio, dispersion value and condition on the self-mode-locked pulse generation and performances are quantitatively analyzed. The result shows that a low laser coupling output ratio can help the formation of a self-mode-locked pulse. The anomalous dispersion self-mode-locked EDFL has a relative high tolerance for dispersion value change but requires high gain energy for mode-locked pulse generation. The normal dispersion one possesses a low mode-locked pulse formation threshold but is relative polarization sensitive. This study is of important reference significance for the investigation of mode-locked fiber lasers.