Abstract: Decomposition of formaldehyde with high-frequency discharge plasma was studied in the paper. The relationships between formaldehyde removal efficiency and applied voltage,discharge current,power supply frequency were mainly investigated.The effect of non-filling,sodium nitrite filling and barium titanate filling were also compared.The experimental results showed that the removal efficiency of formaldehyde increased with increasing applied voltage,discharge current and power supply frequency.Under the same conditions,the reactor with filling had higher removal efficiency than the reactor without filling. Furthermore,the reactor with barium titanate filling had higher removal efficiency than the reactor with sodium nitrite filling.