‘Qianyang’ Bingtang orange was used to study the effects of melatonin （MT） and jasmonic acid （prohydrojasmon，PDJ）.MT and PDJ were sprayed during the fruit expansion stage and the pre-ripening stage to assess the intrinsic quality of the fruits and the expression of CsAN1，a key gene for citric acid accumulation.The results showed that during fruit expansion，fruit soluble solids （TSS） content decreased by 15.07%，30.48% and 19.67% at 10，30 and 50 days after MT treatment compared with the control，respectively，while citric acid content was significantly increased by 18.35%，19.11% and 30.30%.PDJ treatment，on the other hand，significantly reduced the citric acid content，which decreased by 25.10%，36.14% and 34.25% at 10，30 and 50 days after treatment，respectively.During the pre-ripening stage，citric acid content increased by 106.19%，84.82% and 63.10% at 10，25 and 40 d after MT treatment compared to the control group，respectively.PDJ treatment significantly increased the fruit TSS content by 15.59%，2.52% and 9.83% at 10，25 and 40 days after treatment.MT treatment of citrus callus resulted in a 31.06% increase in citric acid content accompanied by significantly upregulated CsAN1 expression.These findings demonstrated that foliar application of MT during both fruit expansion and pre-ripening phases promoted citric acid accumulation and significantly upregulated CsAN1，while PDJ application prior to ripening enhanced the TSS content in fruits.