This study designed and tested a wet electrocyclone with high efficiency for long-term operation. The inner diameter of the collection electrode is 25 cm, and the discharge electrodes consist of seven circular discs with zigzag-shaped edges for particle charging and removal. The tip of the circular saw-type discs is 20lm in diameter and the tip to the inner wall (collection electrode) spacing is 4 cm. Cleaning water near the inter wall was used to keep the collection electrodes clean. Experimental results showed that the collection efficiency of the present wet electrocyclone decreased with an increasing air flow rate. The efficiency for oleic acid (OA) particles was reduced only slightly from 78–92% to 75–90% for particles from 22.1 to 805 nm in electrical mobility diameter (dp) after 6 h of micro-Al2O3 loading test. In the field test, the collection efficiencies of the present wet electrocyclone for submicron SiO2 particles with mass concentration of 20–50 mg/m 3 were also found to keep higher than 93% for continuous 14-day operation. A modified Deutsch-Anderson model was developed to predict the charged particle collection efficiency (gelec,p, %) of nanoparticle as well as larger particles. The present model is gelec;p ð% Þ¼ 1 � expf�½ AðN B