The invention relates to an in-situ cast stainless steel which comprises the following components in percentage by weight: 0.01-0.12% of C, 15.00-22.00% of Cr, 5.00-10.00% of Ni, 1.00-2.50% of Mo, at most 5.00% of Mn, 0.02-1.00% of Nb, 0.80-2.00% of Si, at most 0.03% of S, at most 0.06% of P, at least 0.02% of Re, 0.05-0.30% of N and the balance of Fe. The heat-treatment-free in-situ cast stainless steel has the advantages of fine structure, higher yield strength and toughness than traditional similar nickel-chromium stainless steel, acid/alkali corrosion resistance, favorable machinability, favorable weldability, environmental protection and energy saving, has favorable stress corrosion cracking resistance, crevice corrosion resistance, corrosion wear resistance and cavitation corrosion resistance especially in a chloridion-containing medium and a sea water corrosion environment, does not need excellent heat treatment equipment, and lowers the cost by about 20% as compared with the traditional stainless steel.