Abstract: A new method for the determination of total iron in water with 1,10-Phenanthroline as the chromogenic agent was developed using the quantitative-tube sequential injection spectrometry coupled with a completely set of PLC program system. Under optimized conditions,the detection range is 0~10 mg/L,the linear regression equation is A = 0.0995c+ 0.0421(c: mg/L,n=8) with correlation coefficient of 0.9996. The detection limit was 0.02 mg/L,and the recoveries of environmental samples were between 97.1%~102.0% with the relative standard deviation less than 2.3%.