Burning resistant titanium alloys have been developing since 90s. However, burning resistant mechanism is not clear. Both direct current simulation burning (DCSB) and metal liquid drop methods were used to examine the burning resistant behavior. The reason why some titanium alloys being not burned and its mechanism are analyzed tentatively. The results suggest that a Ti40 alloy exhibits a good burning resistance because of its low melting point, high thermal conductivity, low heat of oxidation and single stable beta structure. On the basis of above analysis, a simple mathematical equation for burning resistant capacity is deduced. This equation shows that burning resistant capacity also has a relation with experimental conditions and the dimensions of sample. Nonburning mechanisms of fast heat dispersion and suspending oxygen transfer are put forward.