A method of producing a Macro Read Only Memory (MROM) memory based on a One Time Programmable (OTP) memory is provided. The method includes: removing a floating gate of a second P-type Metal Oxide Semiconductor (PMOS) transistor of an OTP memory cell for storing data “0” in an OTP memory map, such that the OTP memory cell being transferred to a MROM memory cell for storing data “0”, and retaining an original structure of the OTP memory cell for storing data “1” in the OTP memory map, such that the original structure being used as a MROM memory cell for storing data “1”, thus forming a MROM memory map; and producing a MROM memory according to a MROM memory map. The OTP memory map is debugged to determine data which can be changed into the MROM memory map, and an OTP process can be transferred into a MROM process by adjusting only one mask during a producing process.