Objective To explore association between Helicobacter pylori (Hp) infection in oral cavity and gastric Hp infection through oral cavity and gastric Hp infection testing results analysis, and also to study the effect of Hp infection in oral cavity on Hp eradication treatment. Methods Through Hp saliva test (HPS) and 13C/14C urea breath test (UBT) method, the Hp in oral cavity and stomach were tested in 114 first-visit patients with upper gastrointestinal symptoms (group 1), 129 re-visiting patients who were diagnosed gastric Hp infection with eradication treatment for four weeks (group 2) and 33 volunteers without gastrointestinal symptoms. Results The positive rates of Hp infection by HPS method were 77.19%, 75.97% and 81.82% in group 1, group 2 and group 3 respectively. There was no significant difference between these three groups (χ2=0.47, P>0.05). The positive rate of Hp infection by UBT method in group 1 (52.63%) was higher than those of group 2 (34.11%) and group 3 (21.21%). Compared group 1 with group 2 or group 3, there was significant difference (χ2=8.848, 10.19, P<0.05). There was no significant difference between group 2 and 3 (χ2=2.03, P>0.05). In positive individuals of these three groups tested by UBT method, there was no significant difference of positive rate tested by HPS method (81.67%, 88.64% and 100% of three groups respectively, χ2=2.25, P>0.05). Conclusions The High detection of Hp antigen in saliva indicates that the oral cavity may be the second settlement of Hp beside stomach. The oral medicine haslittle effect on oral cavity Hp infection. The existence of oral Hp may be an important and direct factor of incidence and recurrent of gastric diseases.