The burden calculation of ferromanganese alloy was calculated based on the slag composition and designed product. The calculation results showed the total error rate of this method was 1.53% and the error rate of ore, coke and silicon was 4.66%, 1.71%, and 5.66% respectively, which was much better than using the traditional elements recovery method with the total error rate was 8.00% and the silicon error rate reached to 18.55%. This new method is more accurate than the traditional method and much closer to the actual production data. And it can apply to different ferroalloy factories because it is based on phase diagram and the mass conservation law. At the same time, the calculation result can reflect the gap between enterprise production craft level and ideal production level. This method has certain reference value to improve production technology, product quality and economic profit of enterprise.