Based on strategic guideline of "People's War" and limited capability of blue water powers, China's Navy could only focus on its coastal waters defense capabilities. However, China's naval strategy has shifted from "Littoral defense" to "offshore defense" and energetically built a modern navy due to its rapid grow of economy. The endeavors to build surface warships, submarines, and missiles and to invest enormous budget for changing modern equipment have been compressing battle space of our Air Force and Navy. Additionally, China will never abandon it policy of "invading Taiwan by forces" which is critically increasing threat of our national security. Therefore, Taiwan has to conduct in-depth studies when we face threat from the sea in order to promote new thoughts of force reconstruction and strategic development.