The stable carbon (C) isotope ratio (δ13C) of dissolve inorganic carbon (DIC) in environmental samplesincluding soil extracts and water samples provides insight into the biogeochemical C cycling. The δ13C ofDIC can be measured in gas and solid (carbonate precipitates) states, and precipitates measurement of δ13C ofDIC is more convenient compared to the gases measurement for analyzing a large number of samples. However, it is still uncertain what precipitation conditions, such as pH, headspace, and distilled water, aresuitable. To address the question, we conducted a series of precipitation experiments, followed by δ13C,under different conditions of pH, headspace, and distilled water as well as precipitating agents (SrCl2, BaCl2,and CaCl2). Our results demonstrated that DIC (depleted in 13C) contaminant in double distilled water is themajor error factor to decrease the δ13C. By combining the results from the experiments, we suggest thatreliable δ13C data can be obtained by precipitation under the conditions of using DIC-free tertiary distilledwater, samples with a high DIC concentration, CaCl2 addition as a precipitating agent, pH 10.6, and theabsence of a headspace produces a reliable δ13C measurement.