Simulations on the separation efficiency and the pressure drop of a modified cyclone separator with a novel exhaust under different insert depths (250 mm, 350 mm, 450 mm, and 550 mm), sloping orientations (0 degrees, 90 degrees, 180 degrees, and 270 degrees), contracting angles (15 degrees, 30 degrees, and 45 degrees) and sloping angles (50 degrees, 10 degrees, and 15 degrees) were performed by computational fluid dynamics technique in this study. Results indicate that despite the pressure drop increases to some extent, the separation efficiency of such separators fundamentally exceeds that of the traditional linear-pipe-shaped ones due to the configuration of the novel exhaust can be made to harmonize with the flow field within the separator. Both the separation efficiency and the pressure drop change with the sloping orientation, and they have the same changing rule, the maximum at 90 degrees and the minimum at 270 degrees. The separation efficiency increases firstly and then decreases with increasing insert depth of the novel exhaust, and the maximum appears when the insert depth is 450 mm. The separation efficiency of the modified separator is about 4.6-7.9% higher than that of the traditional one under different sloping angles and contracting angles. Simulation results agree relatively well with the previous experimental results. Besides, based on an overall consideration of separation efficiency and pressure drop, we think that it is the most economic condition when the contracting angle is 30 degrees. However, the contracting angle of 45 degrees is still more suitable when the key problem is the separation efficiency despite its largest resistance loss. (C) 2010 Elsevier B.V. All rights reserved.