The field emission (FE) characteristics of nano-structured carbon films (NSCFs) are investigated.The saturation behaviour of the field emission current density found at high electric field E cannot be reasonably explained by the traditional Fowler-Nordheim (F-N) theory.A three-region E model and the curve-fitting method are utilized for discussing the FE characteristics of NSCFs.In the low,high,and middle E regions,the FE mechanism is reasonably explained by a modified F-N model,a corrected space-charge-limited-current (SCLC) model and the joint model of F-N and SCLC mechanism,respectively.Moreover,the measured FE data accord well with the results from our corrected theoretical model.