Abstract: For the problem of frequent damage in application of LonWorks bus interface of mine-used products, main causes were analyzed including unisolating sending and receiving signals, electrical surge and long-distance transmission. Three protection circuits were gave which are composed of gas discharge tube, polymeric positive temperature coefficent, transient voltage suppressor and electro-static discharge protector. The test result showed that the three circuits can achieve corresponding standards about anti-interference testing of electrical surge and have good effect in use.