A circuit board structure for a low noise block down-converter, for transmitting a first radio-frequency signal and a second radio-frequency signal, the circuit board structure comprising: a first substrate comprising: a first wire for transmitting the first radio-frequency signal; a first grounded wire formed in parallel to one side of the first wire, two ends of the first grounded wire are respectively electrically connected to a first via and a second via; and a second grounded wire formed in parallel to another side of the first wire, two ends of the second grounded wire are respectively electrically connected to a third via and a fourth via; and a second substrate electrically connected to the first substrate, and comprising: a second wire for transmitting the second radio-frequency signal; a third wire formed on one side of the second wire, and electrically connected to one end of the first wire by a fifth via to transmit the first radio-frequency signal; a fourth wire formed on another side of the second wire, and electrically connected to another end of the first wire by a sixth via to transmit the first radio-frequency signal; characterised by a first surface adjacent to the first substrate; and a second surface on which the second wire, the third wire and the fourth wire are formed; wherein the third wire and the fourth wire are indirectly connected to each other, and the first via, the second via, the third via, the fourth via, the fifth via and the sixth via penetrate the first substrate and the second substrate. a first substrate comprising: a first wire for transmitting the first radio-frequency signal; a first grounded wire formed in parallel to one side of the first wire, two ends of the first grounded wire are respectively electrically connected to a first via and a second via; and a second grounded wire formed in parallel to another side of the first wire, two ends of the second grounded wire are respectively electrically connected to a third via and a fourth via; and a first wire for transmitting the first radio-frequency signal; a first grounded wire formed in parallel to one side of the first wire, two ends of the first grounded wire are respectively electrically connected to a first via and a second via; and a second grounded wire formed in parallel to another side of the first wire, two ends of the second grounded wire are respectively electrically connected to a third via and a fourth via; and a second substrate electrically connected to the first substrate, and comprising: a second wire for transmitting the second radio-frequency signal; a third wire formed on one side of the second wire, and electrically connected to one end of the first wire by a fifth via to transmit the first radio-frequency signal; a fourth wire formed on another side of the second wire, and electrically connected to another end of the first wire by a sixth via to transmit the first radio-frequency signal; characterised by a first surface adjacent to the first substrate; and a second surface on which the second wire, the third wire and the fourth wire are formed; a second wire for transmitting the second radio-frequency signal; a third wire formed on one side of the second wire, and electrically connected to one end of the first wire by a fifth via to transmit the first radio-frequency signal; a fourth wire formed on another side of the second wire, and electrically connected to another end of the first wire by a sixth via to transmit the first radio-frequency signal; wherein the third wire and the fourth wire are indirectly connected to each other, and the first via, the second via, the third via, the fourth via, the fifth via and the sixth via penetrate the first substrate and the second substrate.