The invention provides a process 
system for disposal and recycling of 
sewage in oil plants and the corresponding operation method, wherein the process 
system comprises a disposal unit for 
sewage of superhigh concentration, a disposal unit for 
sewage of 
high concentration, a disposal unit for sewage of low concentration and a sewage recycling unit. The invention is characterized in that: after treated by an oxidation 
tower and a sequencing 
bioreactor, the sewage of superhigh concentration is 
effluent and incorporated in the sewage of 
high concentration; after treated by a separation tank, a floatation tank and a biological aerated filter, one part of the sewage of the 
high concentration which comes up to the standards is released, another part is used for 
dilution water of the sequencing 
bioreactor, and last part is incorporated in the sewage of low concentration; after treated by a separation tank, a floatation tank and a biological aerated filter, one part of the sewage of low concentration is 
effluent and used for recycling in a 
reclaimed water system, one part is incorporated in the sewage of high concentration, another part is used for 
dilution water of the sequencing 
bioreactor, and last part which comes up to the standards is released. The process system of the invention realizes respective treatment and water recycling of sewage of high and low concentration in oil plants, can ensure that the 
effluent water quality is stable and qualified and the cost of disposal and recycling of sewage is reduced.