The invention provides a niobium-titanium-nitrogen and titanium-nitrogen composite micro-alloyed HRB400E steel bar and a production method thereof, and belongs to the technical field of iron and steelsmelting. The niobium-titanium-nitrogen and titanium-nitrogen composite micro-alloyed HRB400E steel bar comprises, by mass, 0.21-0.25% of C, 0.50-0.65% of Si, 1.40-1.55% of Mn, not greater than 0.045% of P, not greater than 0.045% of S, 0.015-0.025% of Ti, 0.010-0.020% of Nb, 0.0070-0.0110% of N, and the balance Fe and other impurities. In the production method, ferrosilicon, silicomanganese anda carburant are added at the time of 1/4 tapping, and all alloys are added at the time of 3/4 tapping; the titanium-nitrogen alloy is added at an argon blowing station, and the argon blowing time is greater than or equal to 6 minutes; and high-casting-speed casting powder is adopted for continuous casting, a billet is heated, rolled and fed onto a cooling bed, and finally, the finished product isobtained. According to the niobium-titanium-nitrogen and titanium-nitrogen composite micro-alloyed HRB400E steel bar and the production method thereof, by adding the titanium-nitrogen alloy at the molten steel exposure positon of the argon blowing station, the titanium yield is increased; by reducing the influence of the niobium and titanium content on the quality of the high-casting-speed continuous casting billet, the titanium inclusion in steel is reduced, and the castability of molten steel meets requirements; and by adopting the high-casting-speed continuous casting powder, the cast billet quality is improved.