Abstract: A data writing method and a micro-operation processing system are provided. The micro-operation processing system is adapted to access a plurality of registers and each of the registers defines at least one logic storing area. The data writing method comprises the following steps: executing a first micro-operation; selecting a target area of the first micro-operation, which has been updated by the second micro-operation before, as one of the logic storing areas; assigning each of the first micro-operation and the second micro-operation a respective identification number; determining that a execution order of the first micro-operation is later than a execution order of the second micro-operation according to the identification numbers of the first micro-operation and the second micro-operation; and recording that the target area has been updated by the first micro-operation.