The effects of non-thermal plasma (NTP) induced by a dielectric barrier discharge (DBD) reactor on the stability of turbulent lean and rich premixed ammonia/air flames and the NOx emission characteristics in a modified model gas turbine combustor are experimentally investigated by varying the applied AC voltage, , frequency, , and the mean mixture velocity, . Applying NTP to ammonia/air flames augments the flame stability such that the stable flame regime is extended to lower equivalence ratio, , under fuel-lean conditions or higher under fuel-rich conditions. NTP is found to significantly reduce the amount of NOx emission for both lean and rich premixed ammonia/air flames and the amount of NOx emission is well correlated with . The reduction of NOx emission through NH2 reactions is also identified by measuring NH chemiluminescence.