Based on Asset Choice Theory, treasury bonds issuance depends on interest rates and bonds asset demand of residents, currently, precautionary savings is the key factor to restricting demand of treasury bonds, thus, we need to reexamine the indicators which reflect the ability of residents to buy the bonds in the past. Through the ARIMA model, we estimated and predicted the potential demand for treasury bonds of China, the results show that China’s treasury bonds scale is close to the potential demand and China’s debt bonds issuance space is not optimistic. Because China’s social security system is not complete at present, the proportion of precautionary savings for old-age-care, medical service and education and so on is still high, one of important methods for enlarging China’s treasury bonds issuance space is to complete social security system and to release precautionary savings.