In order to improve the permeability of the soil-bentonite (SB) isolation barrier and its adsorption effect on phenol, a polyacrylamide modified soil-bentonite (PSB) was prepared. The effects of polyacrylamide content, phenol concentration, dry-wet cycles and freeze-thaw cycles on the permeability coefficient of PSB isolation barrier and the adsorption effect on phenol were studied, and the mechanism of these effects were revealed at micro level. The results show that phenol concentration has no effect on permeability coefficient of PSB isolation barrier. The permeability coefficient of PSB isolation barrier increases under dry-wet cycles but remains the same order of magnitude. The permeability coefficient of PSB isolation barrier increases by 1~2 orders under freeze-thaw cycles. Polyacrylamide reduces the permeability coefficient of PSB isolation barrier under dry-wet cycles and freeze-thaw cycles, indicating that it can effectively restrain the destructive effects of dry-wet cycles and freez-thaw cycles. The adsorption rate of phenol on the PSB isolation barrier with 0.7% (mass fraction) polyacrylamide reaches over 69%, which is about 50% higher than that on the SB barrier, and gradually increases with the increase of concentration of phenol contaminated solution. The research can provide theoretical basis and parameter support for isolation and closure of phenol pollution.