Abstract: Granulocyte colony stimulating factor (G-CSF), also known as colony stimulating factor 3 (CSF3), is a glycoprotein (19.6 KDa) consisting of 174 amino acids. G-CSF is a major hematopoietic cytokine that controls the proliferation and differentiation of myeloid progenitor cells into neutrophils. G-CSF can also mobilize neutrophils when the host is infected or has tissue damage. In clinical practice, G-CSF is frequently used to prevent or treat neutropenia or febrile neutropenia caused by radiotherapy and chemotherapy. Recent studies have also shown that G-CSF can promote tumor growth and metastasis by mobilizing tumor-associated neutrophils. This article reviews the role and possible mechanism of G-CSF in promoting tumor growth and metastasis.