Energy is irreplaceable in human life because almost all human activities need energy. The increase of population and the decrease of fossil fuels reserves require humans to look for alternative energy substitutes. Alternative energy especially biomass has abundant and untapped availability. Gasification is a process of converting solid fuel into thermochemical gas by heating it in a gasifier. Unlike combustion where the oxidation process occurs perfectly in one step, gasification converts the chemical energy from carbon compounds in biomass into combustible gas in two stages. Gas produced from this process can be more easily utilized compared to biomass. Its use can be applied as a stove. The combustion test of albizia chinensis shavings waste did not require updraft gasifier with fuel capacity of 1300 grams of the waste. The test was divided into two types of parameters. These parameters used variations in air velocity and variations in fuel mixture. The first parameter was done by giving the air velocity of entry (V) of 0.7 m / s, 0.9 m / s and 1.05 m / s, while the second parameter was done by giving the fuel mixture of charcoal with a percentage of 0%, 25%, 50%, 75%, and 100%. The results of the study reveal the value of thermal efficiency in variations of air velocity, the highest efficiency is at V = 0.7, m / s, which is equal to 28.2%, followed by v = 0.9 m / s which is equal to 23.75% and the smallest is at V = 1.05 m / s which is equal to 17.9%. In the variation of the fuel mixture, the highest thermal efficiency found in 25% charcoal mixture is 28.85% followed by a 0% charcoal mixture of 28.2% and a mixture of 50% charcoal is 22.17%, a mixture of 75% charcoal is 18.91 % and the last mixture of 100% charcoal is 17.10%.