Objective: We aimed to analysis the HER2 gene status and its relationship with p21 protein expression in gastric carcinoma. Methods: Fluorescence in situ hybridisation (FISH) and immunohistochemistry (IHC) techniques were used to detect HER2 gene status and p53 protein in 59 cases of gastric cancer. Results: FISH detection of HER2 gene amplification rate was 16.9% (10/59), HER2 gene amplification in 49 cases without copy number gain and gene amplification were a total of 49.2% (29/59). HER2 protein expression was 42.4% (25/59), HER2 gene amplification rates in patients with +++, ++ HER2 protein expression were 3/3 and 5/8, while in patients with + HER2 protein expression, it was 2/14, there was significant difference (P < 0.05). p21 protein expression rate was 49.2% (29/59), HER2 gene amplification rates and p21 protein expression had significant difference in tumor invasion depth, lymph node metastasis (P < 0.05); had no statistical significance in histological type, age, gender differences (P > 0.05). Conclusion: HER2 gene amplification rate and gene copy number had positively correlation with p21 protein expression, HER2 gene status and expression of p21 protein combined detection can provide a reference value in gastric cancer metastasis, patient’s condition development and prognosis, it also can guide clinical development of individual treatment. Objective: We aimed to analyze the HER2 gene status and its relationship with p21 protein expression in gastric carcinoma. Methods: Fluorescence in situ hybridisation (FISH) and immunohistochemistry (IHC) techniques were used to detect HER2 gene status and p53 protein in 59 cases of gastric cancer. Results: FISH detection of HER2 gene amplification rate was 16.9% (10/59), HER2 protein amplification was 49.2% (29/59) 42.4% (25/59), HER2 gene amplification rates in patients with +++, ++ HER2 protein expression were 3/3 and 5/8, while in patients with + HER2 protein expression, it was 2/14, there was significant difference (P <0.05). p21 protein expression rate was 49.2% (29/59), HER2 gene amplification rates and p21 protein expression had significant difference in tumor invasion depth, lymph node metastasis in histological type, age, gender diffe rences (P> 0.05). Conclusion: HER2 gene amplification rate and gene copy number had positively correlation with p21 protein expression, HER2 gene status and expression of p21 protein combined detection can provide a reference value in gastric cancer metastasis, patient’s condition development and prognosis it also can guide clinical development of individual treatment.