A boot system of an electronic device includes a central processing unit (CPU), a NAND flash, a synchronous dynamic random access memory (SDRAM), and a pulse count unit. The NAND flash and the SDRAM are electronically connected with the CPU. The pulse count unit is electronically connected with the CPU and the NAND flash. The pulse count unit may initialize and enable the NAND flash. The CPU reads a pre-boot loader stored in the NAND flash and loads the pre-boot loader in the SDRAM. The CPU executes the pre-boot loader stored in the SDRAM to boot the electronic device.