Polydopamine (PDA) surface coating has been widely studied in recent years, especially for enhancing the separation performance of membranes. However, their practical application for scale-up production was limited by time consuming, difficulty of coating control and discharge of wastewaters. We report a facile strategy, "living" electrospray, for addressing these limitations. The electrospray process is favorable for the fission and dispersion of micro/nano reactive droplets of dopamine solution, which therefore facilitates the PDA polymerization through enhanced contact surface area to oxygen (four orders of magnitude higher than common 1.0 mL solution) and confined effect. The smooth morphology of the electrospray PDA layer composed of worm-like PDA aggregates with nanopores and thickness can be simply controlled by manipulation of the electrospray time. The fabricated ePDA-10 membrane showed excellent rejection performance for boric acid (87.9%) and organic dyes (98.0%). In addition, the selectivity towards dyes and salts are quite high, as the rejection for salts are relatively low (6.0 +/- 1.8% for Na2SO4 and 1.8 +/- 0.7% for NaCl). The "living" electrospray offers a promising technology for controllably fabricating high performance separation membrane via a zero liquid discharge process.