In this paper, 21 honey samples with excessive amounts of C-4 plant sugar were chosen from 120 specimens obtained from food market.Element analyzer-isotope ratio mass spectrometry (EA-IRMS), liquid chromatography-isotope ratio mass spectrometry (LC-IRMS) and liquid chromatography (LC) were adopted to detect the δ13C values and the amount of C-4 plant sugar. The results indicated that the honey samples with excessive amounts of C-4 plant sugar still occupy a certain proportion in food market and the over-standard rate of this batch was 16.94%. Several samples were detected with serious excessive C-4 plant sugar, one of which haDs the highest amount of 82.35%. The honey samples with excessive C-4 plant sugar can be summarized as the following three categories. (1) Samples with slightly excessive C-4 plant sugar: the standard-exceeding rate of those samples was 7~10% , and their △δ13CF-G and △δ13Cmax values were not far from the requirements of the real honey. (2) Samples adulterated with starch products of C-4 plant source: these samples had a high amount of oligosaccharide and larger △δ13Cma. (3) Samples adulterated with high fructose corn syrup; no oligosaccharide was found in these samples and their δ13CF and δ13CG completely lost the characteristics of C-3 plant.