An integrated mixing/reaction micro flow cell which consists of a sample/reagent mixing channel, a visible port and a reaction chamber was designed, fabricated and tested. A micro cone hole array of macro porous Si was employed for reagent injection part. A visible light transparent PDMS slab was used as the visible port. A Ti-Pt thin film heater and a p-n junction diode temperature sensor were integrated on the reaction chamber to realize feedback temperature control. Uniform mixing and precise temperature control were realized by the fabricated micro flow cell. The striate and simple microchannel structure of the micro flow cell is suitable for multiplexed micro reactor for chemical and biochemical applications.