A novel low-nickel duplex stainless steel of 21Cr-DSS with excellent hot workability was prepared by the alloying design of "C/N+Mn instead of Ni", while the effects of solid solution treatment on its microstructure, strength-toughness and pitting corrosion resistance were studied. The ferrite of 21Cr-DSS during hot-rolling was more susceptible to dynamic softening than austenite. The effect of solid solution treatment temperature on the ferrite/austenite ratio in 21Cr-DSS was more obvious than that of holding time, and the stability of austenite grain size was better than that of ferrite. The strength and toughness of 21Cr-DSS were improved with an increase in solid solution temperature, but when the temperature exceeded 1100°C, its strength and toughness were decreased. The 21Cr-DSS solid solution treated at 1050 °C for 30min had the excellent comprehensive properties, with the PSE (product of strength and plasticity), -40°C impact energy and pitting potential in 3.5% sodium chloride solution having been measured to be about 58.9GPa%, 84J and 0.43V, respectively. The 21Cr-DSS has the more excellent hot workability and strength-toughness than LDX2101, and the similar pitting corrosion resistance. Compared with AISI 304 austenitic stainless steel, the 21Cr-DSS has the higher strength and pitting corrosion resistance.