A measurement of coalbed methane components is directly connected to coalbed methane reserve and successful rate of development engineering. Uncertainty is the key index in marking the reliability degree of measurement results, which comes from three aspects in response values repeatability of coalbed methane components, response values repeatability of standard gas components and accuracy of standard gas. Influence extent is calculated based on testing data of each factor. Uncertainty of standard gas has a larger influence on uncertainty of samples, repeatable measurements of high concentration components leads to higher uncertainty. Uncertainty of coalbed methane components is related to component concentration so that uncertainty of measurement varies with components concentration.

Accuracy of coal bed methane (CBM) concentration tests is closely related to CBM resources evaluation and development. This paper studies the influence of error between desorption gas temperature and atmospheric temperature on the test results, and temperature change on the dead volume of desorption tank. If atmospheric temperature is regarded as temperature of desorption gas in container, some error will be bound during testing CBM concentration. The test result will be larger when desorption gas temperature is higher than atmospheric temperature in a swelling state, vice verse. The larger the temperature difference is, the larger the error will be. If the desorption gas temperature changes largely, this should be considered to estimate this influence on CBM concentration tests. Test result will be larger if desorption gas temperature rises, smaller if decreases. Testing error positively rises with desorption gas temperature changes.