Abstract: The national standard GB/T 13201-91 has recommended the formulae for company width of health protection zone (WHPZ). But it is unable to embody the characteristic of building construction and plane layout of electrolytic aluminum factories and accordingly incurs great differences between calculated results and practical monitoring data, bringing about difficulty in siting of new projects and environmental management of existing company. Starting with the characteristic of uncontrollable discharge of electrolytic aluminum factories and the problem of calculation error by recommended formulae, and on the basis of practical configure and building construction of electrolytic aluminum factories, the authors fully consider the formulae for WHPZ under different conditions, compare all the calculated results of various methods, and find out methods which are more close to practice for WHPZ determination, so as to resolve the difficulty in projects siting for electrolytic aluminum factories incurred by calculation errors of formula in GB/T 13201-91.