Based on the measured optical constants of titanium alloy TC4 in temperature range 298~773K, the bidirectional reflectance distribution function (BRDF) of rough titanium alloy TC4 surface was studied by numerical simulation with the Monte Carlo raytracing approach. The effect of different polarized light incidence, different surface roughness and different temperature on BRDF distribution of rough titanium alloy surface was analyzed. The results show that, the change of BRDF distribution with the incident angle and the roughness of titanium alloy under polarized light is the same as that for unpolarized light. The BRDF of rough titanium alloy surface in incident plane changes with light polarization has the same trend with that of smooth plate. The BRDF peak under TE light incidence is greater than that of TM light. The BRDF peak in specular reflective direction of rough titanium alloy surface decreases with temperature increasing. In the temperature range studied in this paper (298~773 K), the peak changes within 10.2%. The effect of temperature on the BRDF distribution of titanium alloy under TM polarized light is greater than that of TE light, which increases with the increase of incident angle.