Objective To explore the role of miR-140-5p in the development of thyroid cancer and its molecular biological regulation mechanism, the regulatory mechanism of miRNA-140-5P on the invasion and migration of thyroid cancer cells (TPC-1) Methods From January 2021 to January 2022, 36 cases of thyroid malignant tumor and 32 cases of benign tumor were collected. The mRNA expression level of miRNA-140-5P in thyroid malignant and benign tumor tissues was detected by qt-PCR, and the protein expression level of miRNA-140-5P in thyroid malignant and benign tumor cells was detected by WB assay. The difference of miRNA-140-5P expression in the two tissues was evaluated; The experiment introduced miRNA-140-5Pmimics transfected cells, Transwell cell experiment, CCK-8 to detect the migration, invasion and proliferation of thyroid tumor cells. The experiment detected NLRP3 inflammatory corpuscles in thyroid cancer cells (TPC-1), and intervened in the expression of NLRP3 to evaluate the regulatory relationship between miR-140-5P and NLRP3 in thyroid cancer cells. Results miRNA-140-5P showed low expression in thyroid malignant tumor tissues and cells (P＜0.05) However, miRNA-140-5Pmimics could enhance the proliferation, migration and invasion of thyroid cancer cell TPC-1, and reduce the expression of inflammatory mediator NLRP3 in thyroid cancer cells. Conclusion miRNA-140-5P can reduce the proliferation, migration and invasion of thyroid cancer cell TPC-1. There is interaction regulation with NLRP3 inflammatory body in thyroid malignant tumor cells, which may reduce the inhibition of NLRP3, thus stimulating the activation regulation of NLRP3 and inducing the occurrence and development of thyroid cancer