Mechanizing and improving agricultural operations have always been an interest to experts due to the diverse and growing human needs. One of the processes in agricultural products is post-harvest operations. Transferring straw with a mechanized method uses a straw collector. During this process, there is a possibility of mixing gravel and other particles on the ground with the straw. These particles ultimately reduce the quality of the harvested straw. In this study, a laboratory cyclone was constructed and evaluated to handle these challenges. The results of this study were conducted using a factorial experiment in a completely randomized design, with four gravel-to-straw ratios (3.5%, 5%, 10%, and 15%). The experiments were performed at three levels of cyclone inlet opening (1, 0.6, and 0.3), two heights of the vortex finder (0 and 15 cm), and two suction impeller (2574 and 2860 rpm). By performing three repetitions for each of the experiments, a total of 144 data were obtained. The cyclone performance was determined by calculating two separation efficiency factors, the percentage of the separated gravels, and the percentage of straw separated from the mixture. The analysis of variance (ANOVA) and comparison of the means was performed using the Duncan post-test at a 5% probability level using SPSS software version 26. The results showed that the most effective factor in the separation efficiency of gravel and straw was the cyclone inlet opening level. Additionally, the highest separation efficiency occurred at a suction impeller frequency of 50 Hz and a vortex finder position of zero. Also, the cyclone performance was maximum for gravel and straw ratios of 3.5% and 5% respectively.