Pack boronizing of titanium was conducted at 900 °C and holding for 6 h when B4C content in (B4C+ B2O3) was 30% and 40% respectively. Surfaces boride was characterized by X-ray diffraction (XRD). The results show that TiB2 is not found for both B4C contents. TiB is formed on titanium surfaces when the content of B4C in (B4C+B2O3) is 40% at 900 °C, while TiB is very little when the content of B4C in (B4C+B2O3) is 30% at the same temperature. The active B is mainly supplied by B4C. TiB2 is formed at titanium surfaces and the growth of TiB is inhibited as the B4C content is 40% at 1050 °C. Both TiB2 and TiB would be formed based on thermodynamics. TiB is mainly formed at 900 °C because dynamically the diffusivity of B in TiB is higher than that in TiB2, while TiB2 is mainly formed at 1050 °C because the diffusivity of B in Ti is higher than that in TiB