Background　Liver　cancer　is　a　common　second　primary　cancer　in　gastric　cancer　patients,　but　whether　a　gastric　cancer　diagnosis　contributes　to　the　development　of　second　primary　liver　cancer　remains　contentious.　This　study　aims　to　utilize　Mendelian　randomization　(MR)　analysis　to　investigate　the　potential　causal　relationship　between　gastric　cancer　and　second　primary　liver　cancer　from　a　genetic　perspective.　Methods　We　extracted　single　nucleotide　polymorphism　for　gastric　cancer　and　liver　cancer　in　the　East　Asian　population　from　the　Genome-Wide　Association　Studies　database　as　instrumental　variables　and　employed　univariate　and　multivariate　MR　analysis　to　evaluate　the　causal　relationship　between　gastric　cancer　and　liver　cancer.　The　robustness　of　the　findings　was　ensured　through　heterogeneity　and　sensitivity　analyses.　Results　Univariate　MR　analysis　revealed　that　genetic　susceptibility　to　gastric　cancer　in　the　East　Asian　population　was　significantly　associated　with　an　increased　risk　of　liver　cancer　[Inverse-variance　weighted　(IVW):　OR　=　1.252,　95%　CI　1.076-1.457,　P　=　0.004].　Multivariate　MR　analysis　indicated　that　after　adjusting　for　confounding　factors,　the　significant　positive　causal　relationship　between　gastric　cancer　and　liver　cancer　remained　robust　(all　P　＜　0.05).　Furthermore,　no　causal　relationship　was　observed　between　liver　cancer　diagnosis　and　the　development　of　gastric　cancer　in　the　East　Asian　population　(IVW:　OR　=　1.111,　95%　CI　0.936-1.318,　P　=　0.228).　Conclusion　Genetic　prediction　results　suggest　that　gastric　cancer　survivors　might　face　an　increased　risk　of　developing　second　primary　liver　cancer,　implying　the　potential　value　of　routine　liver　cancer　screening　for　gastric　cancer　survivors.