The h-BN powder was synthesized by amorphous $B_2O_3$ and activated carbon at $1550^{circ}C$ in nitrogen atmosphere, whose properties were examined according to $MgB_6$ addition. Amount of $MgB_6$ addition was varied in the range of $0{sim}$10;wt% of the initial mixture. It was observed that $MgB_6$ addition led to an increase in the amount and the grain size of h-BN and decrease in the amount of $B_4C$ forming. When $MgB_6$ added 5 wt%, the amount and crystallinity of h-BN increased as the holding time at the synthesis temperature was prolonged. It was also confirmed that the regularity of three-dimensional ordering of h-BN increases.