In the process of unconventional natural gas and carbon dioxide（CO,2,） replacement extraction of natural gas hydrate,it is important to clarify the synthesis and decomposition mechanism of CO,2,/CH,4, mixed gas hydrate（hereinafter referred to as “CO,2,/CH,4, hydrate”） for the separation of mixed gas,CO,2, sequestration and efficient CH,4, extraction by hydrate method.The secondary synthesis and decomposition experiments of CO,2,/CH,4, hydrate in porous media+deionized water system were carried out to study the effect of memory effect on the synthesis of CO,2,/CH,4, hydrate under the decomposition time of 0.5 h and the decomposition temperature of 5℃ to 25℃.The secondary synthesis induction period,gas consumption and consumption rate,and gas consumption of each component were mainly analyzed.The results show that the induction period of secondary synthesis become shorter when the decomposition temperature is lower.The memory effect reduces the rate of secondary synthesis.The fastest rate of secondary synthesis is achieved when the decomposition temperature is 10℃,and the peak gas consumption rate is 8.10 mmol/min.Under the same synthesis temperature and pressure,the memory effect after heating decomposition increases the synthesis amount of CO,2, hydrate to 1.3 times that of the primary synthesis amount during the secondary synthesis,but has no effect on the synthesis amount of CH,4, hydrate,that is,the effect of memory effect on different guest molecules is different.This study provides a reference for the application of memory effect in hydrate technology.