The wastewater with high pollutant concentration of 20000 mg·L-1（COD）and 2100 mg·L-1（BOD5），high salinity of about 4% and nonbiodegradable from carboxymethyl cellulose production was treated by combined process of microelectrolysis，UASB and biological contact oxidation.The results show that at the optimal conditions the removal of COD by microelectrolysis is 35% and B/C ratio increases up to 0.34.For diluted wastewater，by subsequent UASB anaerobic and two stage biological contact oxidation processes，the removal efficiency of COD is more than 80%，75% and 65%，and the COD value of final effluent is below 100 mg·L-1 and up to the national first-grade emissions standards.The features and mechanism of pollutant removal by microelectrolysis as well as the characteristics of UASB start-up were also studied by means of GC-MS and analyzing granular sludge.The combined process of microelectrolysis，UASB and contact oxidation is of the advantages such as operation stability，high efficiency and shock resistance.