K4169 alloy is a widely used superalloy due to its excellent performance below 650℃. However, the residual impurities in the alloy will dramatically deteriorate the mechanical properties. In this research, the influence of nitrogen content on the microstructure and mechanical properties of superalloy K4169 has been systematically investigated through Thermo-Calc calculation, DSC analysis and quenching experiments with optical microscopy (OM), scanning electronic microscopy (SEM), electron-probe micro-analyzer (EPMA) and transmission electron microscope (TEM). The results indicate that when the content of nitrogen in the alloy increased from 17 ppm to 100 ppm, the precipitation temperature and the quantities of carbides and nitrides are also increased. Moreover it has been proved that the morphologies of carbides can be greatly affected by the content of the nitrogen. A number of large bar-like carbides can be identified when the N content is less than 17ppm and this number is decreased significantly when the content of N is increased to 70 and 100ppm. With the increasing content of N, the morphologies of MC carbides are changed from bar-like to block-like. The elevated temperature performance of this alloy can be greatly affected by the N content while the room temperature performance is rarely changed. When the content of N is increased from 17ppm to 100ppm, the creep-rupture life and elongation are both decreased obviously. Base on this research, as an overall consideration, it is rational to control the N content below 30ppm in K4169 alloy.