Employing statistical design of experiments, the difference in doping behaviors of rare-earth ions and their effects on the dielectric property and microstructure of $BaTiO_3$-MgO-$MnO_2$-($Ba_{0.4}Ca_{0.6}$) $SiO_3-Re_2O_3$ (Re = $Y_2O_3$, $Er_2O_3$) system were investigated. Through the statistical analysis we have found that the amount of $Re_2O_3$ are significantly affecting on the dielectric properties. The $Re_2O_3$ improved the dielectric constant, dielectric loss and R*C constant, so the appropriate contents of $Y_2O_3$ and $Er_2O_3$ were 0.8 ~ 1.2 mol% and 0.8 ~ 1.3 mol%, respectively. The MLCC(mutilayer chip capacitor) with $2.0{ imes}1.2{ imes}1.2mm$ size and 475 nF was also suited for X7R with the above composition. It showed that the dielectric constant and RC constant were 2,839 and 3,675 ${Omega}F$, respectively in the sintering condition at $1250^{circ}C$ in $Po_2$ $10^{-7}$ Mpa.