Trace amounts of copper, lead, cadmium and manganese were determined using a flow injection on-line double chelating resin column pre-concentration FAAS system. The average measurement sensitivities for Cu2+, Pb2+, Cd2+ and Mn2+ increased by factors of 33, 50, 37 and 29 respectively. Sampling frequency was 60 h-1. Relative standard deviations were 2.21%, 3.24%, 1.93% and 3.66% (n = 11) for Cu2+, Pb2+, Cd2+ and Mn2+ respectively. For the national standards (human hair samples, wheat sample and pork liver), the measurement results agreed with the certified values. The method was successfully applied to determinate trace amounts of Cu2+, Pb2+, Cd2+ and Mn2+ species in drinking water and environment water samples.