A transmission circuit including four transmission component sets for Ethernet is provided. For each of the transmission component sets, a first capacitor and a first inductor are cascaded, the first inductor is coupled to the Ethernet connector via the first transmission line (TL), the first capacitor is coupled to the Ethernet chip via the second TL; a second capacitor and a second inductor are cascaded, the second inductor is coupled to the Ethernet connector via the third TL, the second capacitor is coupled to the Ethernet chip via the fourth TL; a first component set is coupled between a first contact and a second contact, the first contact is located between the first capacitor and the first inductor, and the second contact is located between the second capacitor and the second inductor; and a second component set is coupled between the second TL and the fourth TL.