This study is on the analysis of the physical combat strength for the sea battle of ‘Chilchunlyang’ and ‘Myunglyang’ occurred between Chosun and Japan naval forces in Jung-Yu-Jaeran(1597). We used the OODA (Observe, Orient, Decision, Act) theory and the Lancester’s law for the analysis of the physical combat power, and then figured out the accomplished battle power from original physical combat power through OODA theory. Also, we estimated the results of these two sea battles through the Lanchester’s law by applying the accomplished battle power of two naval forces to the operational circumstances. Considering the analysis of the sea battle of ‘Chilchunlyang’, the main reason for the Chosun navy’s defeat was because it did not demonstrate its combat power in an effective way. However, during the ‘Myunglyang’ sea fight, both Chosun and Japan naval forces displayed their own battle power. In this combat, the Chosun naval forces estimated to be get the victory through the analysis of Lanchester’s law. On the other hand, this analysis may offer a basis to presume the spot of the engagement for the naval battle of ‘Myunglyang’. Moreover, the Chosun navy’s overwhelming victory was estimated from the Lanchester’s law assuming that the OODA was sufficiently satisfied by the stages when the conditions were set. Considering the analysis of these two sea battles, we can draw a inference that the reason for Chosun navy’s losing the ‘Chilchunlyang’ sea fight caused by the failure of security operations. In a sense, it is expected to lay the ground work to estimate the aspect of the past battle and the result of future warfare that possibly happen by analyzing the physical combat power.