In accordance with an embodiment, a microfluidic chip including a first cells enrichment system and a second cells enrichment system is provided. Channel layouts of the first and the second cells enrichment systems are symmetric with respect to a reflection plane vertical to the microfluidic chip. Each of the first the second cells enrichment systems includes a first fluid channel, a second fluid channel, a sample channel, an inlet channel, and a filtration chamber. The sample channel of the first cells enrichment system has a first inner wall and a first outer wall. The sample channel of the second cells enrichment system has a second inner wall and a second outer wall. The first outer wall and the second outer wall are both far from the reflection plane. A distance between the first outer wall and the second outer wall is in the range from about 10 μm to about 1 cm.