Abstract: The compressive deformation behavior of a new microalloyed high-strength steel containing 1.79% Al was investigated at temperatures from 900 to 1100℃ and strain rates from 0.01 to 30 s^-1 on a Gleeble-1500 thermo-simulation machine. A hyperbolic sine equation with strain-dependent constants was developed for the steel. The predicted flow stress curves by the constitutive equation well agreed with experimental results, indicating that the constitutive equation can give a relatively accurate estimate of flow stress for the steel. According to processing map analysis, the dynamic recrystallization zone of the steel was determined as 1000 to 1100℃ and 0.01 to 1 s^-1. Microstructure observation showed that dynamic recrystallization occurred in this dynamic recrystallization zone, and in the instability zone, flow localization and necklace structure was observed. Finally, a combination of the constitutive equation and processing map provided a method for comprehensively investigating the hot deformation behavior of the steel under different conditions.