As asteroid mining projects break through the technical barriers, more countries have the plan to become mining pioneers. However, the world currently does not have a complete policy to ensure that asteroid mining can benefit all of humanity. Therefore, exploring its fairness and normality needs to be on the agenda. AHP and EWM are used to construct a global fair distribution model that is more in line with "global interests." It is defined as "global fairness" from the perspectives of the same right to enjoy resources. Moreover, it also guarantees the interests of each country, which maximizes global interests and lays the foundation for the subsequent investigation of the impact of an asteroid mining plan on global fairness. Based on the foundation of the model, the fact is also considered that asteroid mining is currently in the early stage of research and development, which faces the situation of high investment risk and unpredictable returns. To mobilize the enthusiasm of the majority of countries, the different contributions of different countries need to be considered in the construction of the allocation model. Then, a multidimensional index analysis model is established through GRA, which redefines global equity from two dimensions of fairness and contribution.