Physical properties of separator, as important parameters in affecting electrochemical performance and safety of lithium-ion batteries, should be paid more attention. In this study, three kinds of surfactants and dispersants were adopted to investigate their effects on thermal stability, wettability, and electrochemical properties of γ-Al2O3-coating polyethylene-based separator. The experimental results showed that with the synergistic helpfulness of PEG-2000 as a surfactant and D-067 as a dispersant, γ-Al2O3-coating polyethylene separator demonstrates superior thermal stability (no significant thermal shrinkage after heating at 120 °C), electrolyte uptake ability, and improved wettability (contact angle of 27.9 deg). Based on further testing results in Li//mesocarbon microbeads coin cells, the cell with γ-Al2O3-coating polyethylene separator exhibits higher capacity and superior cycling stability than the other two bare counterpart separators at room temperature after 200 cycles. These results demonstrate that the as-prepared separator is highly promising for lithium-ion battery application with the help of a suitable surfactant and dispersant.