The new space economy era has come with the private sector development. Yet in space industry public sector is important with the accumulated knowledge and responsibility of governance. The study of public-private relationship in space economy could bring better understanding on dynamic situation. Europe, United Status and China is on different situation of space economy, which is the result of internal factors; The comparative study could see what factors influence the public-private relationship in space economy, also finding the effect of these factors in Europe, United Status and China could lead to a better understanding of public-private relationship. The thesis combined the study of public-private relationship and comparative study in space sector.