In this study, one year monitoring of NO emissions from purple soil farmlands planted with maize (in the summer) and wheat (in the winter) in rotation was carried out in the field after biochar application in Yanting Agro-Ecological Experimental Station (Chinese Academy of Sciences). The static chamber-gas chromatographic techniques and chemiluminescence NO analyzer were used in the study. Three treatments namely conventional fertilization (NPK), biochar application in combination with fertilizer (BCNPK) and control treatment (CK) without fertilizer and biochar, were applied by randomized design with three replications. Comparisons of NO emission from purple soil farmlands were made between NPK and BCNPK. In addition, CK was used to calculate NO emission coefficient. It was found that NO emission rate was not significantly correlated with soil temperature and soil dissolved organic carbon content, whereas there was a significantly positive correlation between soil moisture (r = 0.204, n = 165, P<0.01) and inorganic nitrogen content (r = 0.486, n = 165, P<0.01). Consequently, soil moisture and inorganic nitrogen content act as the main influential factors for NO emission from purple soil farmland. N fertilizer application or severe soil moisture alternating caused by rainfall could significantly excite NO emissions. The average NO emission rate throughout the trial period in BCNPK and NPK treatments was 20.1 times and 30.9 times higher than that in CK. During the maize season, the significant differences of NO emission rate, cumulative emissions and emission coefficient were observed between NPK and BCNPK (P<0.01). NO emission rate, cumulative emissions and emission coefficient in maize season were decreased by 73.1%, 77.4% and 85.5%, respectively, for BCNPK as compared with NPK. However, the aforementioned three parameters in wheat season showed no significant differences between the two treatments. Moreover, crop yield of BCNPK during the maize and wheat seasons increased by 6.7% and 13.5%, respectively, in comparison with that of NPK. Yield-scaled global warming potential (yield-scale GWP), a comprehensive indicator for the environmental and yield efficiency evaluation, of BCNPK exhibited the decreases of 79.4% and 26.4%, respectively, as compared with that of NPK for both maize and wheat seasons. That is to say, under the same level of nitrogen fertilization, biochar application could not only guarantee the crop production in purple soil farmland not to reduce, but also cut down NO emission. Therefore, biochar application in the purple soil farmland is a promising practice for NO emission reduction.