Self-sharpening effect creates good abrasive performance in magnetic abrasive finishing (MAF); however, abrasive is easily flown away by the centrifugal force, reducing the finishing efficiency in MAF. Therefore, a novel polishing effect of flexible self-sharpening was demonstrated to reveal the excellent abilities in magnetic finishing with abrasive gel (MFGA), and grey relational method based on Taguchi experimental data was applied to obtain the optimal parameters in MFGA. In this paper, a cylindrical rod was finished with silicone gel to compare the MR and SR to those without this medium, and showed the flexible self-sharpening effect in MFGA. The results displayed that high temperature of the gel abrasive (exceeded $110^{circ}C$) during polishing effect induced slow motion of the gel in the working area; hence, old abrasives would be pushed outside the working area during the motion of workpiece and flow motion of gel would pull the new abrasives into the polishing area, creating flexible self-sharpening effect in MFGA. Furthermore, from the grey relational analysis, the best experimental combination of the influential factors was presented; additionally, based on the analysis of variance, concentration of steel grit, machining time and kinds of abrasive dominate the behaviors of MFGA process.