To examine the effects of operational parameters on syn-gas quality and biouel conversion rate under various running conditions, an experimental study of hardwood chip?s gasification in a downdraft gasifier was conducted. The resulting syn-gas had average low heating value of 5.79 ± 0.52 MJ/ Nm3, tar concentration of 14.06 ± 8.54 mg/Nm³, particulate concentration of 3.05 ± 1.79 mg/Nm³, hardwood conversion rate of 2.37±0.24 Nm³/kg, and carbon conversion rate of 98.01 ± 0.53%. This syn-gas is of acceptable quality to be used as a fuel source for internal combustion engine operations. The gasifier?s grate temperature had no evident effects on syn-gas quality and conversion rate within a range of 740 to 817oC. The particulate contents in preiltered syn-gas significantly increased when the gas flow rate changed from 36 to 56 Nm3/h. When the moisture content of hardwood chips increased, tar content of postiltered syn-gas significantly increased, and CO content significantly decreased.