This study aims to analyze the implementation of Law Number 16 of 1964 concerning Fisheries Profit Sharing in purse seine fisheries in Sibolga City, North Sumatra Province, and to evaluate its implementation based on internal and external factors. The study was conducted from February to March 2026 in Sibolga City using a survey method and a quantitative descriptive approach. Respondents in the study numbered 40 people consisting of 8 ship owners and 32 crew members (ABK), who were determined by purposive sampling. Data collection was carried out through observation, interviews, documentation, and questionnaires using a Likert scale. The results of the study indicate that the profit sharing system applied after deducting operational costs is 60% for ship owners and 40% for crew members. The distribution the has fulfil minimum share requirements fisherman laborer as used in research . However , the implementation for results Still face problem in the form of low transparency in delivery results catch , receipts , and costs operational as well as low understanding fisherman to Constitution Number 16 of 1964. Based on internal factors, experience and potential fish resources are the supporting factors for implementation, while transparency is the weakest factor. The most supporting external factors are operational costs and fish prices, while government outreach is the weakest factor. Thus, the implementation of the percentage profit-sharing system is in accordance with the provisions that form the basis for evaluation, but still requires increased transparency, fishermen's understanding, outreach, guidance, and government supervision so that the implementation of profit-sharing can run more fairly and effectively.