The simultaneously efficient removal of radionuclides and heavy metals is an important and challenging topic for aquatic environmental protection. In this work, molybdenum disulfide (MoS2) with heavy metal ion adsorption capacity and positively charged polyethyleneimine (PEI) were used to fabricate a novel layer-by-layer (LbL) self-assembly composite membrane by a simple alternating immersion method. The unique structure with positive charge ensures high removal for toxic metals (RCs(I) = 99.83 %, RSr(II) = 100 %, RHg(II) = 99.2 %, RPb(II) = 98.13 %, RAs(III) = 98.5 %). The inherent low resistance channels in MoS2 provided the optimized composite membrane an elevated water flux. Long-term experiments and membrane regeneration also demonstrated that the membrane possesses exceptional stability and reusability in removing low levels of radionuclides Cs(I) and Sr(II) from water. This study confirms the feasibility of the MoS2-PEI composite membrane for the treatment of contaminated waters containing radionuclides and heavy metals.