A method of manufacturing a non-volatile memory is provided. A substrate includes a memory cell region and a first periphery circuit region. The memory cell region includes a select transistor region. A first gate dielectric layer having a first thickness is formed on the substrate in the first periphery circuit region and the select transistor region. A portion of the first gate dielectric layer on the select transistor region is removed to form a second gate dielectric layer. The second dielectric layer has a second thickness, wherein the second thickness is less than the first thickness.