Recently in natural gas processing, with various feed gases from small to midsize gas reservoirs or shale gas and new compressor drivers of high efficiency that require less or no fuel gas, there has been a growing need of sophisticated nitrogen recovery solutions in producing LNG (liquefied natural gas). In this study two cryogenic nitrogen recovery processes integrated with NGL (natural gas liquid) recovery and LNG production are designed and optimized on the basis of structural analysis of component separation. The difference of each process is the way the nitrogen is removed from the natural gas: an integrated nitrogen recovery unit (NRU) and a standalone one. The former recovers nitrogen in the integrated heat and mass transfer structure with natural gas liquefaction while the latter separates the NRU into an independent section apart from the liquefaction part. These two processes are compared with each other in terms of specific power (kW h/kg LNG ), which is equivalent to the overall process efficiency, with respect to the nitrogen content in the feed gas from 0 to 20 mol %. Consequently, as the nitrogen content in the feed gas increases, the specific power of each process also increases at a different rate where the integrated one changes more slowly. The standalone solution has a priority over the other until around 17 mol % of nitrogen, and after that point, the integrated one reverses it in terms of efficiency. It should be noted that all of the optimization results of each configuration are improved with the reduced specific power by up to 38.6% compared to those from previous studies which have the similar configuration. This study is aimed toward reasonable guidelines for other chemical process designs as well as nitrogen recovery in natural gas processing.