The demand of acquisition success is higher and higher with the progress of the goal of construction of all acquisition. There are many factors which can affect the acquisition success, but in recent years the acquisition failure phenomenon is on the rise because of the unreasonable design of RS485 interface which design are analyzed and summarized. The design principle of various schemes are given, and the advantages and disadvantages of the scheme are conducted. Suggestions and solutions are put forward from RS485 chip itself , data receiving sensitivity, on load capacity, communication reliability 485 interface design.