A new method for simultaneous determination of iron(II), copper(I) and cobalt(II) was established by second derivative peak area spectrophotometry in chromogenic system of 1,10-phenanthroline. The method could avoid disturbing by some ions. The accuracy and sensitivity were improved. There is a linear relationship in the range of 0.0-8.5 microg x mL(-1) for Fe(II); of 0.0-7.3 microg x mL(-1) for Cu(I); and of 0.0-5.9 microg x mL(-1) for Co(II). The method has been applied to simultaneous determination of iron(II), copper(I) and cobalt(II) in aloe with satisfactory results. The average recovery is 98.6%-102% and the RSD is 0.1%-0.2%. There is no remarkable difference between these results and those of ICP-AES method.