This study presents a study of the lenless CMOS (Complementary Metal-Oxide-Semiconductor) sensor integrating a NI LabVIEW image processing program for particles recognition and size analysis The micro-image recognition and size analysis system includes a lenless CMOS sensor, a PDMS (poly-dimethylsiloxane) microfluidic detection chip by a lithography process and a NI LabVIEW image processing program.In the image processing program, the particles number and size can be distinguished by the pixel size utilizing the raw image acquired from the lenless CMOS sensor.The system test results are verified in the commercial optical microscope by the same scale photograph.