Dual titanium boride layers consisting of continuous TiB2 top-layer and TiB whisker sublayer were formed on the surface of Ti6Al4V alloy using powder-pack boriding technique. An iso-thickness diagram of the whole boride layer was fitted with the data of thickness of the coating, treatment time and process temperature using Sigma Plot10.0 software. Growth kinetics of the titanium boride layer were analyzed by measuring the extent of penetration of TiB2 and TiB whisker as a function of boriding time in the range of 5-20 h and boriding temperature in the range of 1000-1100 ℃. By the linear regression analysis of growth kinetics of titanium boride layer, the diffusivity K and average diffusion activation energy (Q) of boron atoms in Ti6Al4V alloy were calculated, respectively. Dual titanium boride layers consisting of continuous TiB2 top-layer and TiB whisker sublayer were formed on the surface of Ti6Al4V alloy using powder-pack boriding technique. An iso-thickness diagram of the whole boride layer was fitted with the data of thickness of the coating , treatment time and process temperature using Sigma Plot 10.0 software. Growth kinetics of the titanium boride layer were analyzed by measuring the extent of penetration of TiB2 and TiB whisker as a function of boriding time in the range of 5-20 h and boriding temperature in the range of 1000-1100 ° C. By the linear regression analysis of growth kinetics of titanium boride layer, the diffusivity K and average diffusion activation energy (Q) of boron atoms in Ti6Al4V alloy were calculated, respectively.