An interface apparatus cascading system, characterized in comprising: a host, comprising a first controller and a first interface port, wherein the first controller provides data transmission of a first channel and a second channel through the first interface port, wherein the first channel and the second channel are independent with each other; a first-type interface apparatus, comprising a second controller, a second interface port, and a third interface port, wherein the second interface port is connected in series with the first interface port, the third interface port is connected with the second interface port, data of the first channel is transmitted to the second controller through the second interface port and to the third interface port through the second controller, and data of the second channel is directly transmitted to the third interface port through the second interface port, wherein the data of the second channel cannot be transmitted to the second controller; and a second-type interface apparatus, comprising a third controller, a fourth interface port, and a fifth interface port, wherein the fourth interface port is connected in series with the third interface port, the fifth interface port is connected in series with the fourth interface port, the data of the second channel are transmitted to the third controller through the fourth interface port and to the fifth interface port through the third controller, and the data of the first channel is directly transmitted to the fifth interface port through the fourth interface port, wherein the data of the first channel cannot be transmitted to the third controller. a host, comprising a first controller and a first interface port, wherein the first controller provides data transmission of a first channel and a second channel through the first interface port, wherein the first channel and the second channel are independent with each other; a first-type interface apparatus, comprising a second controller, a second interface port, and a third interface port, wherein the second interface port is connected in series with the first interface port, the third interface port is connected with the second interface port, data of the first channel is transmitted to the second controller through the second interface port and to the third interface port through the second controller, and data of the second channel is directly transmitted to the third interface port through the second interface port, wherein the data of the second channel cannot be transmitted to the second controller; and a second-type interface apparatus, comprising a third controller, a fourth interface port, and a fifth interface port, wherein the fourth interface port is connected in series with the third interface port, the fifth interface port is connected in series with the fourth interface port, the data of the second channel are transmitted to the third controller through the fourth interface port and to the fifth interface port through the third controller, and the data of the first channel is directly transmitted to the fifth interface port through the fourth interface port, wherein the data of the first channel cannot be transmitted to the third controller.