In this paper, a study on efficiency increment (operation efficiency) of Kahnooj titanium pilot plant electrical roll separator with optimization of variable and effective parameters (crona voltage intensity, feed temperature and size distribution, rolls speed, crona electrodes position and splitter position) on operation efficiency is investigated and obtained results are presented. To achieve this aim, parameters were classified and then tests designed with Taguchi method. Feed size distribution tests in laboratory scale and the other tests in pilot plant scale were performed. Optimized values of crona intensity voltage, feed temperature, rolls speed was found to be 22 kv, 109, 154 rpm. However, the optimum position of crona electrodes, the first, second and third splitters were obtained to be 6, 8, 10 and 10 cm. In the position of optimum values, operation efficiency was increased from 35.9% to 46.1%. Moreover, operation efficiency in laboratory scale with d80 of 259 microns feed was maximized and operation efficiency of 46.0% obtained.