In order to investigate the reliability of micro-interconnecting copper pillar bump under thermal-electric coupling, the test chip with electrified daisy chain copper pillar bumps was designed and manufactured. And 9 sets of thermoelectric coupling accelerated life test were carried out respectively, which the resistance increased by 10% was considered as the failure threshold to get the mean-time-to-failure of thermoelectric coupling reliability. Combined Black's equation with accelerated life test, the reliability model of copper pillar bump, to take the consideration of Joule heat effect, was established. The exponent for current density and activation energy for EM are calculated as 17.75 and 0.63eV. The result shows that current stressing is the main acceleration stressing which could influence the life of copper pillar bump. The corrected Black's equation is appropriate to describe the reliability of copper pillar bump interconnection. The failure process of copper pillar bump is dominated by the dissolution of Cu atom, the growth of Cu3Sn and crack propagation. And the soldering interface of solder cap is considered to be the failure weakness under thermal-electric coupling.