A multifunctional all-fiber polarization-maintaining nonlinear amplifier system is proposed and investigated. Two Erbium-doped polarization-preserving gain fibers are used to amplify the seed laser and split into four output points with different transmission fibers to obtain four stable ultra-short pulses with different durations, which vary from tens of fs to ps level. And the output powers are tens of mW and can be changed with different output point. The seed laser in this process has a repetition rate of 113 MHz, a pulse duration of about 450fs, and different absorption coefficients for the two gain fibers. It is demonstrated that the proposed fiber laser with varied pulse duration can be potentially applied in laser detection, terahertz generation, and even different types of material processing.