Abstract: The effects of P and Ga elements on the oxidation resistance of SnCu0.7 Pb-free solder were studied through static and dynamic oxidation experiments. X-ray diffractometer (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS)were used to study the phase and element distribution of the oxide slag. The static oxidation experiment shows that P can effectively improve the oxidation resistance of SnCu0.7 at 270℃and with the increase of P content, the amount of alloy oxide slag decreases first and then increases.When the P content is 10^-4, the amount of oxide slag is the smallest. After adding Ga, the solder has good oxidation resistance at 270℃and 400℃. The dynamic oxidation experiment shows that:P and Ga elements can be enriched in the oxide slag; adding P can significantly improve the dynamic oxidation resistance of SnCu0.7, while the addition of Ga produces sticky slag and reduces the dynamic oxidation resistance; when P and Ga are added together, Ga-P complex oxides are formed in the oxide slag, which inhibits the activity of Ga so that the solder does not produce sticky slag; adding Ga can increase the oxidation resistance temperature of SnCu0.7-100P, but it will accelerate the consumption rate of P, thereby reducing the oxidation resistance time of the alloy.