Various heat-treatments were conducted to Ti-48.1at%Al and Ti-48.3at%Al-1.2at%Mn alloys tasted by plasma arc melting system. Mechanical properties, microstructure and high temperature oxidizing behaviors of as-tasted and heat-treatment alloys were investigated. Ti-48.1Al and Ti-48.3Al-1.2Mn alloys were decreased in strength according to increased of heat-treatment temperature. Oxidizing weight gain of Ti-48.1Al alloy which conducted at 1273°K was linearly increased. In case of adding Mn to alloy, there was no rapid increase of oxidizing weight gain during early time.