An image guided navigation system comprises a memory, a locator, a processor and a display. The memory stores a plurality of CT images and a software program. The locator is capable of indicating a direction to a surgical area, and the indicated direction of the locator is defined as a first direction. The processor is electrically connected to the memory and the locator. At least one corresponding image corresponding to the first direction is obtained from the plurality of CT images by the processor executing the software program. The at least one corresponding image comprises at least one simulated fluoroscopic image. The display is capable of showing the at least one corresponding image.