Objective The expression pattern of TET family proteins was investigated in a mouse lung cancer model. Methods The mice were divided into three groups (with 10 mice in each group): control group (Con), urethane- induced group (Ure), and HU-treated group (Ure-HU). Urethane ( 800 mg / kg) was injected intraperitoneally for 10 weeks to establish the mouse lung cancer model in the Ure and Ure-HU groups. After 10 weeks, the Ure-HU group was given the drug HU (500 mg / kg) for 21 days. The morphology was observed thereafter, while qPCR and western blotting were used to analyze the expression patterns of TET1, TET2, and TET3 in the three groups. Results Compared with that of the Con group, the weights of the Ure group and Ure-HU group decreased. Morphological observation revealed lung tissue lesions in the Ure and Ure-HU groups. qPCR result suggested that the expression of TETs was decreased in the Ure group(P < 0. 05). After HU treatment, the expression of TET1 and TET2 was increased in the Ure-HU group (P < 0. 05). The data from western blotting were consistent with the qPCR result . Conclusions The expression of TETs was abnormal in a mouse lung cancer model induced by urethane. These result suggest that TET1 and TET2 play important roles in lung cancer.