Abstract: In order to strengthen the supervision of the quality of royal jelly, a method for royal jelly adulteration identification was established using elemental analyzer-isotope ratio mass spectrometry (EA-IRMS). Base on the δ¹³C values of 106 authentic royal jelly samples from different production areas, the δ¹³C value limits for the authentic royal jelly samples were proposed. The δ¹³C value of royal jelly should be lower than or equal to -21.5‰ and the δ¹³C difference between protein and royal jelly (Δδ¹³Cp-r) should be higher than or equal to -0.95‰. Based on the above criteria, 65 royal jelly samples are confirmed adulterated with C-4 plant sugar in 131 commercial royal jelly samples. As a conclusion, the EA-IRMS method can effectively identify the exogenous C-4 plant sugar adulteration in royal jelly.