This study presents a blockchain-based security sharing framework designed to enable fine-grained access control for personal data, addressing the growing concerns surrounding data privacy and security in the digital age. As individuals generate vast amounts of sensitive information, traditional data sharing mechanisms often fall short, leading to unauthorized access and data breaches. Our framework harnesses the decentralized and immutable properties of blockchain technology to enhance data protection while granting users greater control over their personal information. By utilizing smart contracts, we enable the definition of specific access policies that dictate who can access data and under what circumstances. Through rigorous simulations and evaluations, we demonstrate that our approach effectively safeguards personal data while ensuring compliance with privacy regulations. The findings reveal that this framework not only enhances data security and user empowerment but also provides a transparent solution for managing personal data access in an increasingly interconnected world. This research contributes significantly to the field of blockchain applications in data security, offering a robust mechanism for secure personal data sharing.