AMS-02 is a magnetic spectrometer which aims an indirect search for dark matter through cosmic-ray positrons and antiprotons as well as direct search for antimatters and study on the origin of cosmic rays. It was launched by space shuttle Endeavor and installed on the International Space Station in May/2011. Since then it is taking data for about two years. Although it's final goal is a long observation for 10~20 years, we have already identified about 680 million electrons and positrons in the energy range, 0.5~350 GeV, which will enable us to determine very precisely the positron fraction.