We evaluated the effects of Na, K, Ca, and the steam-to-biomass (S/B) ratio on gasification efficiency during syngas production. The results show that H2 production was positively correlated with the S/B ratio. However, increases in the S/B ratio were limited because excessive steam decreased the reactor temperature and hampered the gasification process. Regarding the effects of alkali metals on syngas composition, we found that the addition of either Na or K increased the molar percentages of H2 and CO, but decreased CH4 and CO2. The results also clearly show that the addition of Na or K improved the yield of syngas, the carbon conversion efficiency, and the cold gas efficiency. Improvements were especially pronounced with K. Furthermore, Ca had different interactions with Na and K during gasification. When Na and Ca existed simultaneously, H2 production was enhanced.