Alkali lignin, a by-product of commercialized paper making process, is an abundant and environmental-friendly material. In this paper, polyacrylontrile (PAN) -based hollow fiber was fabricated by one-step wet-spinning technique through blending with alkali lignin at different ratios. The phase diagram of the blends was determined by titration method. When alkali lignin is added into the PAN solution, the clouding points move away from polymer-DMSO axis, and miscibility gap increases. The phase separation of PAN was slowed down by mixing with alkali lignin which resulted in the formation of hollow structure and promoted the pore formation in the wall. This work clearly explains the roles that alkali lignin plays in the system consisting of polymer, solvent and nonsolvent, and provides a feasible method to produce PAN-based hollow fibers. (C) 2018 Elsevier Ltd. All rights reserved.