This paper studies the difference of solute distribution in microstructure of Pd40Ni40P20 alloy solidified on board a Chinese Retrievable Satellite and on the ground.Compared with those in normal gravity condition(1g),it was found that P content was lower but Pd content was higher in the primary phase,however in the eutectic region P content increased but Pd content decreased in microgravity condition(μg).By evaluating the mass transport coefficients in both cases it can be concluded that the difference in solute distribution both in 1g and μｇ conditions was due to the existence of buoyancy convection in the ground-based experiments.