The range analysis was applied to clarify the importance sequence of K2HPO4, (NH4)2SO4 and MgSO4 in the orthogonal experiments. Table 4 shows the range analysis results of L9(34) orthogonal experiments of ethanol yield. Results showed that the range (R) of factor B was 9.95, which ranked the first. Factor C was 3.57, which ranked second. Factor A was 2.80, which ranked third. The blank was 2.0, which ranked the last and meant that each factor was reliable. Generally speaking, the greater R-value of a factor represents greater effect on the final ethanol yield. According to the range, the order of influence could be determined as (NH4)2SO4>MgSO4>K2HPO4. Judged by the k value of different factor, the optimal inorganic salts supplement dose for improving ethanol yield was determined as A2B1C2. Thus, the optimal inorganic salts supplement dose was determined as follows: K2HPO4 0%, (NH4)2SO4 0.20% and MgSO4 0.05%. (NH4)2SO4 could adjust and stabilize pH of fermentation juice [17], and S in the form of (SO4)2− could be utilized by the yeast cells as the nutrient material. Meanwhile N in NH4+ can be used as the nitrogen source[18]. Mg2+ is also an activator of some enzymes in yeast cells [17]. As a result, adding such inorganic salts will promote the ethanol yield.