In this work, the combined effects of vibration parameters on the circularly screening processes are analysed based on the Taguchi Orthogonal experiment method. First, numerical investigations of the screening process including the average particle velocity and screening efficiency of different particle size fractions are presented. The variations of the average velocity and the screening efficiency of different particle size fractions for both spherical and non-spherical particle models are examined. The effect of vibration intensity on the screening process is discussed and the potential error induced by the analysis of a single factor on the screening performance is demonstrated. Then, the orthogonal test data of average particle velocity and screening efficiency for 16 cases are analysed by using the direct analysis method. The combined effects of amplitude, frequency and the inclination angle of the screen deck on the screening performance are discussed based on the calculated average values of each level of the factors. The corresponding optimal combinations of the three factors for two screening performance indexes are obtained, respectively. The effect weights of the vibration parameters on the screening performance indexes are also obtained by comparing the ranges of the factors. This work should be helpful for the understanding of the combined effects of operation parameters and provides essential references for efficient operation and optimal design of a vibrating screen. (C) 2017 Elsevier B.V. All rights reserved.