A method for adjusting a programming/erasing time in a memory system is disclosed. In one embodiment, a programming/erasing step is executed for writing data into the memory system, wherein the programming/erasing step is executed until a programming/erasing time and/or a cycle number per unit of time is reached. Then, a verification step is executed for verifying the data written into the memory system to determine if the data written into the memory system is correct so as to obtain a verification result. When the verification result is incorrect, a setting step is executed for setting the programming/erasing time and/or the cycle number per unit to new values. Thereafter, the programming/erasing step is repeatedly executed for writing the data into the memory system after the programming/erasing time and/or a cycle number per unit of time is set to the values.