Abstract: Basic rules for making greenhouse gas sampling equipment were summarized, and a nested sampling chamber was designed to measure methane emission fluxes of different kinds of wetland around Dongting Lake. The advantage of the chamber was its adjustability of height and volume. When transported or not in use, reduced volume could be realized by setting the top of the chamber into the middle of it; when used, expanded volume could be generated by setting the top of the chamber upon the middle of it. The height of the chamber changed when numbers of middle parts increased. Field observation showed that the average methane emission flux of paddy around Dongting Lake in April was 10.37 mg/(m²·h), which confirmed the reliability of applying the chamber in wetland methane monitoring. It was remarkable that sampling operation should be completed in 40 minutes in order to avoid instability of methane emission caused by internal environment change of the chamber.