The invention provides a flash memory gate structure, preparation method and application. Compared with a gate structure with equal width in the prior art, the gate structure formed by adopting the preparation method in the invention includes a control gate having a first width and a floating gate having a second width, wherein the second width is larger than the first width, in other words, while critical dimensions of the floating gate is not changed, critical dimensions of the control gate is decreased, so that on the premise of ensuring that performance of a flash memory is hardly influenced, thereby increasing the distance between the control gate and a contact hole, reducing the probability of occurrence of accidental conduction between a word line and a bit line in the flash memory, improving validity of the flash memory in cyclic operation, and increasing the preparation yield and reliability of the flash memory.