It is found that in a buffer solution of HAc-NaAc (pH-6.0), iron (III) and aluminium (III) react with ethylene glycol diethy diaminoteracetic acid (EGTA), pyrogallol red (PR) and cetylpyridinium bromide (CPB) to form quarternary complex. Micro iron (III) and aluminium (III) can be simultaneous determined by the first derivative spectrophotometry of the quarternary complex. The RSD for the determinations of iron and aluminium are 4.5% and 1.1% respectively, and the recoveries are 93%-98% and 95%-102% respectively. This method has been applied to the determination of micro iron and aluminum in quartz sand with satisfactory results.