The invention relates to a preparation method of a memory and belongs to the technical field of semiconductors. The preparation of a control grid and a floating grid of a memory bit unit and a memory word line is sequentially completed on a semiconductor substrate, in addition, the etching on a second coupling conducting layer is completed step by step, and the preparation of lead-out electrodes of other semiconductor devices on the substrate is completed under the condition of not influencing the structure of the memory. In the method, the chip area of a split grid flash memory is effectively reduced through the word line sharing memory under the condition of maintaining the electric isolation performance of the chip unchanged, and meanwhile, the over erasing problem can also be avoided. In addition, in the preparation method of the memory provided by the invention, the memory array word line and the lead-out electrodes of other semiconductor devices on the substrate are synchronously completed, any process steps and process difficulty are not added, and the semiconductor structures of the memory and the like cannot be damaged and influenced in the preparation process.