A data caching method and a computer-readable medium storing a program executing the method used in a cache system where a data replacing parameter is used for a data replacement rule, are provided to assist determining whether a user data has to be replaced or not. The data caching method and the program rely on the cache system to determine whether to replace the user data when the resource consumed in fetching the user data is lower than a predetermined level. However, when the resource consumed in fetching the user data is higher or equal to the predetermined level, the value of the data replacing parameter mentioned above is replaced within a predetermined period, such that the user data could be maintained in the cache system.