Objective Long non-coding RNA (lncRNA) HMGA1P4 has been previously reported to be upregulated in gastric cancer (GC). This study aims to investigate the role of HMGA1P4 in cisplatin (DDP)-resistant GC. Patients and methods HMGA1P4 levels in DDP-resistant GC tissues and cells were determined. Regulatory effects of HMGA1P4 on proliferative and apoptotic abilities in DDP-resistant GC cells and their parental cells were assessed. At last, expression levels of genes associated with multidrug-resistance (MDR) (MDR1, MRP1, mTOR and HIF-1α) and apoptosis (Bax, Bcl-2 and Caspase3) were determined in DDP-resistant GC cells. Results Results revealed that HMGA1P4 was upregulated in DDP-resistant GC tissues and cells. Overexpression of HMGA1P4 stimulated proliferative rate and suppressed apoptosis in both DDP-resistant GC cells and their parental cells. Moreover, in DDP-resistant GC cells, overexpression of HMGA1P4 upregulated MDR-related genes and downregulated apoptosis-related genes. Conclusions HMGA1P4 is upregulated in DDP-resistant GC tissues and cells, and triggers the progression of DDP-resistance in GC.