Abstract A direct no-standards quantitative analysis method of binary alloy is developed and applied to multicomponent alloys including 7-components and 8-components steel samples in which the contents of some components are about 0.25-1.0%. As compared with the indirect no-standards method (Buss et al.), the accuracy of the present method is generally better and the analytical time shorter. It only needs about 10 seconds in calculating the constituents of a 8-components alloy from their characteristic X-ray intensities using a computer with a speed about 130,000 cps. The analytical results of binary alloys, especially NaCl, using this modified method are better than before.