Objective To observe the effects of incomplete argon-helium cryoablation on migration, invasion and pulmonary metastasis of residual tumor cells in a Lewis lung carcinoma (LLC) mouse model, and to preliminarily explore the underlying mechanism. Methods A total of 24 female C57BL/6N mice were subcutaneously injected with LLC cells to establish xenograft models. When the tumor volume reached approximately 70 mm³, mice were randomly assigned to 4 groups: blank control group (BC group), sham-operation group (Sham group), incomplete cryoablation group (ICA group), and complete cryoablation group (CA group), with 6 mice in each group. The ICA group received approximately 70% tumor ablation with 30% residual tumor; the CA group underwent complete cryoablation; the Sham group received needle puncture only without ablation; and the BC group received no intervention. Mice were euthanized 3 d post-treatment. Lung tissues were harvested for hematoxylin-eosin staining to detect metastatic foci. Residual tumor tissues were collected for Western blotting analysis of matrix metalloproteinase 9 (MMP9) expression. Primary tumor cells were isolated, and scratch assay, Transwell migration and invasion assays were performed to evaluate cell migration and invasion abilities at 0, 24 and 48 h. Results The incomplete cryoablation LLC mouse model was successfully established. Pulmonary metastatic foci were observed in the ICA group but not in the other 3 groups. The expression level of MMP9 in the ICA group was significantly higher than that in the BC and Sham groups (both P＜0.01). Cell function assays showed that the migration and invasion rates of primary cells in the ICA group were significantly higher than those in the BC and Sham groups at 24 and 48 h (all P＜0.05). Conclusion Incomplete argon-helium cryoablation enhances migration and invasion abilities of residual LLC tumors and promotes pulmonary metastasis, which may be associated with upregulated MMP9 expression.