A novel self-healing semi-interpenetrating network hydrogel based on a natural polymer (konjac glucomannan, KGM) and synthetic polymer (polyacrylamide, PAAm) is prepared by a simple one-pot synthesis method. The hydrogels show excellent self-healing ability at ambient temperature without the need for any stimulus or healing agent and high recovery degrees (up to 73% tensile strength) can be achieved at a prolonged healing time. The healed gels exhibit high tensile strength (up to 66 kPa) and high elongation (up to 1200%). And the effect of the NH3.H2O content, the ratio of KGM to acrylamide (AAm) and the cross-linker content on the self-healing efficiency have been investigated. The combination of structural transition of PAAm and the intermolecular hydrogen bonding is essential for self-healing property of the hydrogels. (C) 2016 Elsevier Ltd. All rights reserved.