In order to understand the behaviors of dissolution of TiN inclusions in liquid titanium alloys and evaluate the roles of alloying elements in the diffusion process, the diffusion and phase transformation near alpha region of TiN\Ti interface in C_pTi and Ti-6Al-4V have been studied. The artificially embedded TiN sponge particles dissolved into liquid alloys. The concentration profiles of nitrogen in the interfaces have been determined by microprobe for either as-cast or heat-treated samples. The experimental results show that the concentration profiles of nitrogen in phase transformation region show a steep change. The alloying elements Al and V retard the diffusion of nitrogen and dissolution of TiN particles.