A tumor cell xenograft model in zebrafish, and methods of constructing and using the same. Primary cells dissociated from the tumor tissue of a patient are transplanted into zebrafish, so as to obtain a patient-derived tumor xenograft model. The tumor xenograft model retains the pathological features of human gastric cancer tissues in clinic, has higher clinical relevance, and can be used in the systematic research into the mechanisms underlying the proliferation, metastasis, spread and drug resistance of tumors, and to screen effective drugs for tumor treatments.