An apparatus for automatically testing CMOS magnetoresistive biochips is disclosed. The apparatus includes: means for directly or indirectly applying physical pressure to the fluid pumping chamber in a cartridge; a liquid injector for injecting liquid into the reaction chamber in the cartridge through an inlet or inlets in fluid connection to said reaction chamber; a CMOS magnetoresistive biochip located in the reaction chamber in the cartridge; means for applying a magnetic field to said CMOS magnetoresistive biochip in the cartridge; an electronic module for communicating with and supplying power as well as control signals to said biochip; a microprocessor to control and coordinate the aforementioned components; and a user interface for information processing. The apparatus provided by the present invention reduces the complexity of operation and enhances the detection sensitivity to a great extent.