Objective To develop a quality standard of Citrus limon oils.Methods Limonene in Citrus limon oils was identified by capillary gas chromatography and its content was determined by internal standard method.A polyethylene glycol elastic quartz capillary column (30 m of length,0.32 mm of internal diameter,0.25?m of film thickness) was used,column temperature being 90℃and split ratio being 5:1.Results In the range of 0.0627 mg/mL～4.0136 mg/mL for limonene,an equation was obtained:Y=1.53321X-0.05275,r=0.999 9.The average recovery of limonene was 97.2 % with RSD being 0.6 %.Conclusion The method is stable and reliable,and can provide evi- dences for the development of quality standard of Citrus limon oils.