Recent work has shown that amplification and compression of ultrashort fundamental solitons in an erbium-doped nonlinear amplifying fiber loop mirror not only can avoid soliton distortion caused by nonlinear effects such as self-phase modulation etc., but also overcome the difficulty of adiabatic amplification that the amplifier length must increase exponentially with the input pulse width. In this paper, the effects of loop and input pulse characteristics on the device performance are investigated. Numerical simulation has shown that, for given input pulses, the device performance is fairly insensitive to variations in the loop parameters such as the the loop length, loop gain and coupler 's power coupling coefficient ratio. For a fixed amplifying fiber loop mirror, the input pulse parameters such as pulse shape and initial input power fluctuation and the higher-order effects have small influence on the device performance. The initial frequency chirp of the input pulse has a larger influence on the output pulse-width but a small influence on the output soliton-quality.