In the study to reduce the error on the method of sampling pine needles to monitor the atmospheric concentration of polychlorinated biphenyls(PBCs),it was found that: 1. Concentration of PCBs almost linearly increased from new to three-years-old pine needles, so that the biomonitoring method using pine needles canbe applied to measuring long-term contamination from air in a local area. Needles of differernt age should not be mixed in sampling but be seperately analysed .It no good idea comparing PCB concentrations of differently aged needles. 2. Concentratio n of PCBs on pine needles had nothing to do whit the indivisual and age of the pine tree. 3. Concentration of PCBs on pine needles growing avobe was lower than that on needke below. 4. Concentration of PCBs on pine needles locatied in poorly ventilative places such as needle of a forest was lower than that on needles in well-ventilated areas.