Gastric cancer (GC) is one of the most common malignancies worldwide. Previous studies have focused on long non‑coding RNAs (lncRNAs), which have important roles in the development and progression of GC. The present study aimed to clarify the expression and function of lncRNA small nucleolar RNA host gene 12 (SNHG12) in GC. The expression and the clinical characteristics of GC were analyzed in the samples from patients with GC and matched adjacent normal tissues. The present study determined that SNHG12 was significantly overexpressed in GC and its expression level was highly associated with tumor size, tumor‑node‑metastasis stage, distant metastasis, lymphatic metastasis. Patients with high SNHG12 expression had a short survival period. Additionally, inhibition of SNHG12 in GC cell lines SGC‑7901 and AGS suppressed cell growth, colony formation, proliferation and invasion. MicroRNA (miR)‑320, a putative target gene of SNHG12, was inversely correlated with SNHG12 expression in GC tissues and cell lines. In addition, the present study determined that miR‑320 was directly regulated by SNHG12 and suppression of miR‑320 expression reversed the inhibitory effects of SNHG12 siRNA on GC cell proliferation and invasion. These findings revealed that SNHG12 acts as a tumor promoter by directly targeting miR‑320 in GC, suggesting a potential novel biomarker for the diagnosis and prognosis of GC.