The Software Defined Network (SDN) is one of the best commonly used network management architecture in recent years. The main aim of SDN is enabling flexibility and simplicity in network operation and management via centralized controller. This approach is allowing administration to efficiently oversee, configure, and optimize various network devices like switches, routers, and access points from a unified control point. SDN encounters numerous challenges, including latency issues, scalability, packet forwarding, security and cost. Among this security is a major concern for SDN, particularly due to the threat of Distributed Denial of Services (DDOS) attacks, which pose a significant risk to the SDN environment. Despite ongoing advancement in tools and technology, the detecting and mitigating DDOS attack within SDN remains a challenging task. As of now no fully efficient solution has been developed to effectively cope with the challenges posed by DDOS attack in SDN environment. The proposed Mutual Information Entropy Calculation method (MIEC) is a rapid and simple solution for detecting DDOS attack and improve previous entropy detection algorithm. Experimental result further shows more accurate outcomes and faster reporting in comparison to previous methodologies.