The invention relates to a gastric cancer detection primer and a kit thereof. The kit comprises a digital PCR premix solution, a liquid drop stabilizer, an miRNAs primer probe mixed solution, and a stem-loop reverse transcription primer mixed solution for performing RNA reverse transcription; the miRNAs primer probe mixed solution comprises an upstream primer for detecting hsa-mir-20a, hsa-mir-17, hsa-miR-106b and hsa-mir-16, a probe and a general downstream primer for detecting hsa-mir-20a, hsa-mir-17, hsa-miR-106b and hsa-mir-16. The stem-loop reverse transcription primer mixed solution comprises a stem-loop reverse transcription primer for reverse transcription of hsa-mir-20a, hsa-mir-17 and hsa-miR-106b, wherein hsa-mir-20a, hsa-mir-17 and hsa-miR-106b are markers, and hsa-mir-16 is B-actin. The gastric cancer detection kit can rapidly, conveniently and accurately detect the expression level of miRNA as the gastric cancer early diagnosis marker.