The invention provides a bio-detection device, including a carrier, a plurality of spacers, an electronic circuit, and a package layer, wherein an open platform is formed. The carrier includes a test region and a signal transmission wiring, wherein the test region is configured to carry a fluid under test. The spacers are located on the test region and electrically connected to two different voltage levels to form a capacitor for sensing a capacitance of the fluid. The spacers are connected to the signal transmission wiring. The electronic circuit receives and processes a sensing signal corresponding to the capacitance of the fluid. The package layer covers a portion of the carrier but does not cover the test region. The open platform is formed whereby a user can easily put in the fluid. The open platform has a bottom which includes the test region, and an area of the open platform is defined by the spacers and the package layer.