Abstract: The kinetics of austenite grain growth in the ultra-high strength steel 23Co14Ni12Cr3MoE, was investigated by microstructure observation and theoretic model analysis at 800-1 150 ℃. The results indicate that the average austenite grain size of the steel increased when the heating temperature increased and the holding time prolonged. And the growth of austenite grain followed the Beck′s equation. The best austenitizing temperature should be controlled in 850-950 ℃. The grain growth exponent increased gradually with the increase of heating temperature, and the average activation energy was 256.62 kJ·mol-1 in the temperature range of 800-1 150 ℃. The equation of austenite grain growth for 23Co14Ni12Cr3MoE steel in isothemal heating process was established.