Electrokinetic and contact angle measurements were used to discuss the interracial interaction on bio-leaching of pyrite mineral. Surface energy parameters of pyrite mineral and thiobaeillus ferrooxidans were Gbtained by calculating according to formula of Youngs equation and contact angle measurements. The results show that surface energy of thiobacillus ferrooxidans is much higher than that of pyrite mineral, and the reaction of pyrite mineral with thiobacillus ferrooxidans causes the reduction of the pyrite surface energy. The interfacial interaction energies between pyrite mineral and thiobacillus ferrooxidans were also obtained based onpolar interfacial interaction theory and electrokinetic and contact angle measurements. The thermodynamics approach only considering Lifshitz-van der Waals and Lewis acid-base interaction fails to explain the adhesion behavior of the bacteria, but theextended Derjaguin-Landan-Verwey-Overbeek theory concerning Lifshitz-van der Waals and Lewis acid-base and the electrostatic can exactly predict interracial interaction.