Abstract: [WT5BZ]Nitrogen oxide (NO_X) is one of the most important lightingproduced molecules, primarily because it facilitates chemical reactions in the troposphere that determine the concentrations of ozone (O₃) and of the hydroxyl radical (OH). NO_X source, LNO_X mechanism and their significance on climate change are introduced for understanding the estimate of LNO_X, which is a research hotspot in atmospheric chemistry and lighting physics. Then, the main methods and results of estimate on LNO_X are summarized. The conclusions show that, in situ measurement, laboratory simulation, theoretical extrapolation and retrieval of satellite data are the major research methods in this field. Through these methods, NO_X production per unit lightning energy or unit lightning channel length are obtained, then combined with the total energy or channel length of lightning, the LNO_X production in local or global is estimated by extrapolation or numerical modeling. Due to the different region, thunderstorm and even lightning are presented remarkable difference, and the parameters chosen by different researchers are various, leading to the diversity of results. In the past three decades, the mean value of relatively accurate production calculations has been 5.2(2.8~9.1) Tg/a. Therefore, advanced NO_X observations of in-situ and space measurements should be analyzed to realize the LNO_X mechanism. Appropriate NO_X parameters should be chosen in varied intensity thunderstorm and individual lightning to reduce the parameter uncertainties. On that basis, atmospheric chemical model is integrated to simulate LNO_X generation, development and the influence of other air composition regionally and globally. Thus, the role of LNO_X in global climate change would be better recognized.