The rare presence of circulating tumor cells (CTCs) in the bloodstream has made their recording and separation one of the major challenges in the recent decade. Inertia-based microfluidic systems have received more attention in CTCs separation due to their feasibility and low cost. In this research, an inertial microfluidic system is proposed using a curved expansion-contraction array (CEA) microchannel to separate CTCs from white blood cells (WBCs). First, the optimal flow rate of the proposed microfluidic device was determined to maximize the separation efficiency of the target cells (CTCs) from the non-target ones (WBCs). Then, the efficiency and purity of the straight and curved-CEA microchannels were assessed. The experimental results indiated that the proposed system (curved-CEA microchannel) can offer the highest efficiency (-80.31%) and purity (-91.32%) at the flow rate of -7.5 ml/min, exhibiting ∼11.48% increment in the efficiency compared to its straight peer.