Abstract Surrogacy as a new form of reproduction has begun to gain popularity since the 1970s.However, in the past few years, with the rapid advance of reproductive technologies and the convenience of international transportation and communication, transnational surrogacy has become a global trend of surrogacy. This new trend facilitates people who suffer from infertility in countries where surrogacy is not available legally or technically, but it raises many legal and ethical issues, leading to debates on the potential harm and conflicts it may cause. Among all the concerns, the regulation of legal parentage is the most challenging and attention-needed issues. In transnational surrogacy cases, as the participants (the surrogate mother, the commissioning mother and the partner of the commissioning mother) come from more than two countries and the regulations regarding surrogacy between countries vary greatly, the legal conflicts on the issues of surrogacy occurs. Children born as a result of transnational surrogacy often cannot get legally recognized by the home country even though their parent-child relationships with the commissioning parents are established by the birth country. As a result, these children become parentless or stateless in their home countries. This paper will examine the conflict of regulation on determining legal parentage in the transnational surrogacy cases. Using a comparative legal research method, I will analyze the ways of legal parentage establishment in the selected domestic law. By comparing the current resolutions in dealing with legal parentage conflicts, I suggest applying the principle of "Best Interest of the Child" in solving legal parentage problems because it protects the interest of the children. Keywords Transnational surrogacy, legal parentage, parentage determination, parentage recognition, the best interest of the child