The Erlanggou section of the Mesoproterozoic Jixian System in Qishan county of Shaanxi province is located in the southern margin of North China Craton. It contains a set of marine carbonates, which are subdivided ascendingly into the Longjiayuan Formation and Xunjiansi Formation. A total of 184 carbon and oxygen isotope samples were collected and tested. The results show that the δ 13C values range from -1. 747‰ to 1. 144‰ with an average value of -0. 523‰, which is generally stable. δ 18O values show a range between -8. 662 ‰ and -2. 540 ‰, most of which falls between -5. 5 and -3 ‰, with an average value of -4. 469 ‰. It is low- amplitude and high- frequency oscillated. The C isotope profile reveals a cyclic evolutionary trend, which can be divided into four subcycles. The carbon and oxygen isotopes profiles are consistent with the previous research results of the Jixian System in the Yanshan area of North China. A negative excursion event of about 2‰ occurred at the top of the Xunjiansi Formation, which is roughly correlated with the negative excursion event from the top of Wumishan Formation to Hongshuizhuang Formation at the Jixian section of Tianjin province. The fluctuation of carbon isotopes and the abundance changes of algae (stromatolites) indicate that sea level was constantly changing in the study area during the Mesoproterozoic. In addition, the C and O isotope results of the Erlanggou section are highly consistent with that in the Hornby Bay Group in Canada and Avzyan Formation in Ural of Russia. This feature conforms to the most stable feature of global carbon isotopic composition during the Mesoproterozoic and should be the response to the global uniform paleo- ocean setting.