In order to effectively remediate the dissolved petroleum hydrocarbon contaminants in aquifer, low temperature hydrocarbon degrading bacteria-peat-coarse sand and peat-coarse sand were adopted respectively to construct peat biobarrier and peat barrier. And the ratio of packing media, the removal efficiency of BTEX and PAHs were investigated through barriers in remediation of petroleum hydrocarbon contaminated groundwater. It is found that the hydraulic conductivity and available porosity of mixed media were 1.17×10-4 m/s, 7.5% respectively when peat and coarse sand at the optimum volume ratio of 20:80. For peat barrier, the removal rates of BTEX were 32.63%-79.15%, sorption life was 50-55d, sorption capacity of peat barrier to BTEX was xylene > ethylbenzene≈toluene> benzene, effluent concentration of naphthalene, α-methylnaphthalene, β-methylnaphthalene and phenanthrene were all below 2.85μg/L. The removal efficiency for BTEX, PAHs were 83.6%-97.83%, 97.48%-99.85% through remediation by peat biobarrier, and have an obviously effect on contaminants biodegradation, the degrading rates of BTEX were 75.66%-90.16%. The study indicated that removal mechanisms of hydrocarbon contaminants were peat sorption and biodegradation for peat biobarrier, peat had strong sorption capacity to petroleum hydrocarbon contaminants, especially for PAHs, contaminants biodegradation could efficiently prolong the sorption life of peat barrier.