Although the anticancer effects of Huaier extract have been widely investigated, including anti-proliferate, anti-angiogenic and anti-metastatic activities, the mechanisms are not well understood. This study aimed to elucidate the inhibitory effect of Huaier extract on tumor growth in cervical cancer cells and its molecular mechanisms. Cell viability and motility were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, colony assays, migration, and invasive assays, respectively. The distribution of the cell cycle was analyzed by flow cytometry. Huaier inhibited cell viability of SiHa and C33A cells in a time- and dose-dependent manner; cell migration and invasiveness were also suppressed; Huaier was able to cause G2/M cell cycle arrest in C33A cells. The western blot results confirmed Huaier dose-dependently increased expression of phosphorylated c-Jun N-terminal kinase (JNK), p-38 and downregulated the expression of phosphorylated extracellular signal-regulated kinase (ERK) in a time- and dose-dependently manner. In vivo experiments showed that Huaier significantly suppressed the tumor volume of SiHa cell xenografts. These data suggest that Huaier may inhibit tumor proliferation in cervical cancer via the JNK/p38 signaling pathway.