Abstract: The effect of heat treatment on the high temperature ductility of 00Cr24Ni13 austenitic stainless steel casting billets was investigated by heat treatment experiment, therma-compression test and thermal tensile test. The result showed that δ ferrite morphology in the casting billet could be significantly changed through the heat treatment process. After air cooling from 1200℃ for 3 h, large area of continuous reticular δ ferrite in the casting billet completely changed into dispersed granular phases. Compared with the casting billet before heat treatment, heat-treated samples which are composed of granular δ ferrite had a higher value of deformation resistance at different compression temperatures, but there was no sharp deterioration in deformation resistance, the thermal simulation tensile strength remained almost the same and the reduction of area (Z) at the same temperature increased obviously. The temperature region of Z ≥ 60% extended from 1150-1280℃ to 1050-1300%, and the high plasticity (Z ≥ 80%) range is about 150% (1150-1300℃).