A stable Q-switched Er-doped fiber (EDF) laser is successfully obtained by using a black phosphorus (BP)/polymethyl methacrylate (PMMA) film as the saturable absorber (SA). To avoid the oxidization of nanomaterials, the BP nanoparticles are fabricated via a liquid-phase exfoliation method and then embedded into a PMMA film that possesses excellent optical transparency in the selected spectrum range. The modulation depth (MD) of the BP/PMMA film SA is 14.3% and the saturable intensity (I-sat) is 6.9 MW/cm(2). By inserting the BP/PMMA film into the EDF laser cavity, we achieve the stable passive Q-switching operation over the wavelength range from 1561.21 nm to 1564.16 nm. The repetition rate increases from 10.348 kHz to 30.098 kHz, and the pulse duration decreases from 25.01 mu s to 2.98 mu s by altering the pump power from 9 mWto 90 mW. The maximum single pulse energy is 283.91 nJ. To the best of our knowledge, 283.91 nJ is the largest single pulse energy among the Q-switched fiber lasers with BP as the Q-switcher at the 1.5 mu m wavelength region. The experimental results evidently show that the BP/PMMA film SA can work as a promising Q-switcher for large pulse energy fiber lasers. (c) 2018 Optical Society of America