<p>This paper systematically investigates the influence of varying carbon contents on the microstructure and properties of nitrogen-containing Cr13-type corrosion-resistant die steel in quenched and tempered states. The results indicate that the steel microstructure after quenching at 1030&#xa0;°C mainly consists of martensite and undissolved carbides. As carbon content increases, martensite morphology gradually transitions from lath to cryptocrystalline martensite, accompanied by reduced grain size, and undissolved M₂₃C₆ carbides maintain constant size but increase in quantity. Elevated carbon content raises steel hardness from 50.8 to 56.3 HRC, reduces toughness from 5.4 to 4.4&#xa0;J, causes brittle fracture of all specimens under impact loading, and degrades pitting corrosion resistance. During 600&#xa0;°C tempering, numerous nanoscale M₂₃C₆ carbides precipitate. With carbon content increasing from 0.15% to 0.19%, tensile strength rises from 993 to 1047&#xa0;MPa; further increases to 0.24% reduce it to 1032&#xa0;MPa. Meanwhile, toughness continuously declines from 12 to 7.5&#xa0;J. Correspondingly, the fracture mode shifts from purely ductile to mixed ductile-brittle. Owing to the synergistic effects of carbon and nitrogen, the steel with 0.19% carbon content exhibits superior mechanical properties at a fixed nitrogen content of 0.1%</p>