Objective To investigate the effect and mechanism of ZCCHC12 on epithelial-mesenchymal transition and invasion of differentiated thyroid cancer cells. Methods A total of 50 patients with differentiated thyroid adenocarcinoma admitted to Hebei General Hospital from May 2017 to December 2018 were selected, and set as differentiated thyroid cancer group. In addition, 50 subjects for healthy examination in the hospital during the same period were selected as the healthy control group.The contents of PKA/cAMP response element binding protein (CREB) and p21 in serum was detected by ELISA. Western blotting was used to detect the relative expressions of CREB and p21 in HUM-CELL-0097, TPC-1 and FTC-133 cell lines. TPC-1 cells and FTC-133 cells were taken and set up blank control group (normally cultured), NC si group (transfected with non-specific siRNA),and ZCCHC12 si group (transfected with ZCCHC12 siRNA), ZCCHC12 si+NC pc group (transfected with ZCCHC12 siRNA followed by the transfection with pcDNA.3.1), ZCCHC12 si+CREB pc group (transfected with ZCCHC12 siRNA followed by the transfection with pcDNA.3.1-CREB), ZCCHC12 si+NC si group (transfected with ZCCHC12 siRNA followed by the transfection with non-specific siRNA), ZCCHC12 si+p21 si group (transfected with ZCCHC12 siRNA followed by the transfection with p21 siRNA). Western blotting was performed to detect the relative expressions of ZCCHC12, CREB, P21, E-cadherin and N-cadherin proteins. Transwell method was used to detect the cell invasion ability. Results Compared with healthy control group, the serum content of CREB increased (P<0.05), and of p21 decreased (P<0.01) in differentiated thyroid cancer group. Compared with HUM-CELL-0097 cells, the content of CREB increased (P<0.01), and of p21 decreased (P<0.01) in TPC-1 and FTC-133 cells. Compared with NC si group, the relative expressions of E-cadherin and p21 protein increased, while the relative protein expressions of CREB and N-cadherin and the number of cell migration decreased (P<0.01) in ZCCHC12 si group. The expression of p21 protein in ZCCHC12 si+CREB pc group was lower than that in ZCCHC12 si+NC pc group (P<0.01), which reversed the promoting effect of interfering ZCCHC12 on p21 protein expression. Compared with ZCCHC12 si+NC si group, the relative expression of E-cadherin protein significantly decreased, while the relative expression of N-cadherin protein and the number of cell migration were significantly increased (P<0.01) in the ZCCHC12 si+p21 si group, which reversed the inhibitory effect of ZCCHC12 interference on the epithelial-mesenchymal transition and invasive capacity in differentiated thyroid cancer cells. Conclusions Interfering with ZCCHC12 can effectively inhibit the epithelial-mesenchymal transition and invasion of differentiated thyroid cancer cells by regulating CREB and p21, providing a certain theoretical basis for the treatment of differentiated thyroid cancer.