Abstract: In the process of piezoresistive pressure sensor packaging,the thermocompression wire bonding was studied to meet the outer interconnection of silicon gauge.A novel instrument of thermocompression wire bonding was developed.Microstructures of the joint interface were analyzed by SEM.The thermocompression wire bonding strength was tested with bonding tester.The strength was over 0.17 N.Through the investigation of the metallic compound in the interface of Au-Al and increasing of its diffusion depth with temperature,the temperature of substrate was kept between,150℃ and 200℃ and the temperature of the solder chisel was kept at about 150℃ in operation.The interface of thermocompression point was tested with good reliability.The instrument was easy to be operated and fitted for batch fabrication of piezoresistive pressure sensor.