Abstract: With the intensification of global climate change,the monitoring and analysis of greenhouse gases (GHGs) have become increasingly critical.As a pivotal component in greenhouse gas observation systems,the fully automatic ultra-low temperature cold trap plays an essential role by eliminating water vapor from sampled gases,thereby enhancing the sensitivity and accuracy of the analytical instruments and extending their operational lifespan.To address issues such as the retention time from the sampling pump to the analytical instrument,the duration of the impact of gaseous water on CO₂ and CH₄ concentration measurements,and excessive H₂O(g) ingress during cold trap tube switching (exceeding technical thresholds),this study reduces the structure of the cold trap and analyzes its effects on system retention time,performance,and the impact duration on greenhouse gas concentration measurements during cold trap switching.By reducing the internal volume of the cold trap tube,the residence time of the sample gas in the cold trap is shortened.Additionally,the conventional solenoid valve drainage method is replaced with peristaltic pump drainage method to ensure that the water outlet maintains in a constant drainage state,preventing the return of indoor air to the cold trap tube,improving drainage efficiency and eliminating the interference from indoor air on the measurement of sample gas.The results show that after optimization,the retention time of the sample gas through the pretreatment system is significantly shortened,with an average time is 57.58 s,which is less than 1 min,meeting the specified requirements.the peak H₂O(g) concentrations during the three cold trap tube switching events are 12.93×10^-6,14.36×10^-6,and 12.94×10^-6,all meeting the technical requirements of being less than 40×10^-6.The impact durations on the measurement of greenhouse gas concentration are 1.75 min,1.53 min and 2.01 min,respectively,all meeting the technical requirement of being less than 3min,ensuring that the sample gas meets the requirements of the analytical instrument.The structurally optimized ultra-low temperature cold trap not only fulfills the stringent requirements of the analyzing host for the measurement of sample gas,but also provides new ideas for the design of the greenhouse gas monitoring systems,further improving the performance of the ultra-low temperature cold trap,and providing more accurate data support for addressing climate change and achieving the goals of "dual carbon".