Stable isotope tracer techniques, especially the use of carbon and nitrogen stable isotopes have been extensively applied in agricultural chemistry, geochemistry, and environmental chemistry. Calibration of mass spectrometers for precision in analysis of carbon and nitrogen isotope ratios are directly related to the reliability of the tracer experiments. Currently, as reference materials enriched in carbon and nitrogen stable isotopes are not readily available for calibration, it is advisable to verify accuracy of the instruments and comparability of their analyses through comparison between laboratories in carbon and nitrogen isotope ratio detection capability. For that, in 2013, a total of 14 testing laboratories and a total of 17 sets of equipment all over the country were invited to participate in the comparison sponsored by the Institute of Soil Science, Chinese Academy of Sciences. Agricultural, ecological and environmental samples were used in the test for comparison. The institute also prepared a variety of test samples, including carbon and nitrogen-containing chemical fertilizers, soils and plant samples. For analysis of stable isotopes, samples natural in isotope abundance and different in isotope enrichment level were also prepared. Besides solid samples, there were 3 kinds of N₂O and CO₂ gas samples different in isotope abundance for analysis. The Z score method was used to measure reliability of the analysis in each laboratory. In this paper, comparisons between the 14 laboratories were summarized in 2013.