A microfluidic diffraction device is developed for determination of CTC/bacteria from human whole blood with a home-constructed laser beam system. We design the optical structuretransfer the structure to transparent plastic substrate. The plastic diffraction die is modified with antibodies of the target to combine a fluidic system as a microfluidic diffraction chip. When human whole blood with CTCs/bacteria flows through the chip, the number of cells/bacteria can be obtained directly with label-free. The devices has been applied in clinical diagnosis of oesophagealendometrial cancer.