SBR process ( the combination of anaerobic phase with aerobic phase) is used to treat formaldehyde wastewater.In anaerobic phase,C₅H₈(OH)₄ and formaldehyde wastewater are degraded primarily by middle- high temperature biological catalyt ic acidification, and the hydrolysate of the above phase is further degraded in aerobic phase. The results show that the removal rate of formaldehyde can be 98% and the removal rate of COD_Cr is more than 90%. BOD₅ load rang is from 0.04 to 0.08 kg/ ( kgMLSS?d) formaldehyde load rang is from 0. 011 to 0. 022 kg/ ( kg MLSS·d), anaerobic reaction time is 16 hours and aerobic reaction t ime is 11 hours.