GDC-0575, as a novel oral small-mol. Chk1 inhibitor, has attracted the attention of many pharmaceutical companies due to its strong synergistic effect with gemcitabine in sarcoma cells.Therefore, it is particularly important to develop an efficient synthesis process for preparing GDC-0575. 1 H-pyrrolo [2, 3-b] pyridine with a wide range of sources and low price was used as starting material.High quality GDC-0575 was obtained with a total yield of 25.2 %, which underwent eight steps of oxidation, chlorination, nitration, bromination, aromatic nucleophilic substitution, hydrogenation, condensation and deprotection, resp.The purity of API reached 98.8 %, which met the requirements of pharmacol. and toxicol. studies in the early stage.