A firmware updating system and method are provided. The firmware updating method includes configuring a host to digitally sign a firmware to be updated, and configuring an electronic device to perform an authorization verification on an update tool, and only the update tool that passes the verification has an update permission. The update tool uses an encryption algorithm to encrypt the firmware to be updated that includes a digital signature. After the encryption is completed, the host sends the update tool to the electronic device through the update tool. The electronic device then uses a decryption algorithm to decrypt the received firmware to obtain the firmware to be updated including the digital signature, and write the firmware to be updated into a firmware storage area to be updated. The electronic device then verifies the digital signature in the firmware to be updated.