This research aims to analyze the issues of legal protection for Micro, Small, and Medium Enterprises (MSMEs) from the perspective of positive Indonesian law and to formulate a reconstruction of a legal harmonization model that can achieve legal certainty in the digital trade ecosystem. The research uses a normative legal method with a legislative approach and a conceptual approach thru analysis of the legal regime for MSMEs, Electronic System Trade (PMSE), contract law, consumer protection law, and business competition law. The research results indicate that legal protection for MSMEs is not yet effective due to the fragmentation of regulations, which results in a normative vacuum regarding the limits of authority of digital platforms as gatekeepers, algorithm transparency, accountability for digital decisions, protection against unbalanced standard clauses, and guaranties of procedural rights for MSMEs. This research offers a novelty in the form of a legal harmonization model reconstruction thru the integration of MSME law, electronic commerce law, contract law, and competition law into a coherent regulatory framework. The model is built on six fundamental principles: protection of MSMEs, freedom to operate, healthy business competition, legal certainty, algorithm transparency, and platform accountability, which are implemented thru a ban on unilateral account suspension, prior notice obligation, recognition of the right to be heard, independent internal review mechanisms, independent dispute resolution, and transparency in changes to terms and conditions and algorithms. This harmonization model is expected to strengthen legal certainty, achieve contractual justice, and create a more accountable and fair digital platform governance for MSMEs.