This study aimed to evaluate the anticancer activity and cell division arresting by dandelion methanolic extract on breast cancer cell line MCF-7 cancer cell line. For achieving this goal, cytotoxicity assay (MTT assay), multipara system assay: High Content Screening (HCS) which include (viable cell count VCC; membrane permeability MP; cellular mitochondrial permeability CMP; nuclear intensity NI and cytochrome C releasing ), reactive oxygen species detection and cell cycle phases division were tested. The results of this study showed the ability of the plant to reduce cancer cell viability in a dose-dependant manner within IC50 (141.0) in comparison to IC50 of (334.4) on the human normal cell line (WRL-68). Furthermore, the results of HCS demonstrated the ability of plants to enhance apoptosis of cancer cells and increase the production of ROS from cancer cells treated with plant extract and doxorubicin drug in comparison with negative control (50.07±2.2, 53.03±2.6 vs. 44.77±1.4) respectively. Also,  the results of the cell cycle for control, 400 µg\ml of dandelion extract and doxorubicin drug showed the ability to arrest the division of cancer cells at G1 phase by decreasing its transmission to S, G2, and M phases of the cell cycle (62%, 59% and 62.46% at G1) (27.46%,26.50% and 24.66% at S Phase) (16.50%, 20.50% and 18.46% at G2\M) respectively. All these effects are attributed to the active compounds (secondary metabolites) such as terpenes, polyphenols, and different minerals that possess anticancer activity against different cell lines like MCF7.