In a method for protecting software of a computing device, a hypertext preprocessor (PHP) software program of the computing device is encrypted using an encryption rule to obtain an encrypted file. When the encrypted file needs to be decrypted, the method determines whether a predetermined hardware lock is connected to the computing device. When the predetermined hardware lock is not connected to the computing device, the method displays a prompt that indicates the predetermined hardware lock is not connected to the computing device. When the predetermined hardware lock is connected to the computing device, the method decrypts the encrypted file with a decryption rule corresponding to the encryption rule.