Objective To study the application of contrast-enhanced ultrasound combined with multi-slice spiral CT in the diagnosis of gastric cancer. Methods A total of 116 cases of patients with gastric cancer diagnosed by pathology from March 2015 to March 2018 were analyzed retrospectively. All patients were given contrast-enhanced ultrasound and multi-slice spiral CT before operation. The accuracy of the single method and combined method for Borrmann classification and TNM staging were analyzed. Results The total accuracy of combined diagnosis for Borrmann classification was higher than that of contrast-enhanced ultrasound and of multi-slice spiral CT (91.38% vs 83.62% vs 77.59%) (P<0.05). The total accuracy of combined diagnosis for gastric cancer T stage was higher than that of contrast-enhanced ultrasound and of multi-slice spiral CT (88.79% vs 78.45% vs 70.69%) (P<0.05). The total accuracy of combined diagnosis for gastric cancer N stage was higher than that of contrast-enhanced ultrasound and multi-slice spiral CT (86.21% vs 74.14% vs 62.93%) (P<0.05). There was no statistically significant difference in the total accuracy of gastric cancer M stage by contrast-enhanced ultrasound, multi-slice spiral CT and combined diagnosis (P>0.05). Conclusion Preoperative contrast-enhanced ultrasound combined with multi-slice spiral is better than single diagnosis in the diagnosis of accuracy rates of Borrmann classification, T stage and N stage. The combination of the two methos helps to improve the accuracy of preoperative diagnosis.