Currently, the PLA Navy (PLAN) has a total strength of 235,000 officers and men, which include 25,000 naval aviation, 25,000 costal guards, and 40,000 marines. According to the data from globalsecurity.com, the PLAN has 1 aircraft carrier, 3 amphibious transport docks, 26 destroyers, 49 frigates 61 submarines (of which 11 are nuclear-powered), one corvette, 122 missile boats, 231 patrol vessels, 107 mine countermeasures vessels, 5 replenishment oilers and a large fleet of auxiliary vessels. The naval aviation are divided into 10 division, which include 6 fighter division, 3 bombardment aircraft division, and 1 training division. It has 541 combat aircraft, which include 150 bombardment aircrafts, 400 fighters, and about 100 helicopters.
The costal guard has 50-80 ground-to-ship missile launchers, 200-300 cannon, and 500-700 antiaircraft guns. The PLA Navy is the second largest navy in the world, only behind the United States Navy in terms of size. However, due to the historical reason, China has always been centered on the Army. The PLA Navy has large numbers of vessels, but tonnage is generally small, and the technical characteristics of the ship are also relatively backward. This situation results that the Chinese Navy is only able to fight in offshore area after the founding of the People's Republic of China period, which doesn’t match the total scale of the PLAN.
The Japan Maritime Self-Defense Force (JMSDF) has an official strength of around 45,500 active personnel. According to the data from globalsecurity.com, as of 2013, the JMSDF operates a total of 134 vessels, including; 4 helicopter destroyers (or helicopter carriers), 6 large aegis destroyers (or cruisers), 2 guided missile destroyers (DDG), 16 destroyers (DD), 13 small destroyers (or frigates), 6 destroyer escorts (or corvettes), 16 attack submarines, 29 mine countermeasure vessels, 6 patrol vessels, 3 landing ship tanks, 8 training vessels and a fleet of various auxiliary ships. The fleet has a total displacement of approximately 450,000 tons.
The JMSDF aviation maintains a large naval air force, including 191 fixed-wing aircraft and 148 helicopters. Most of these aircraft are used in anti-submarine warfare operations, which include 80 most advanced anti-submarine and maritime surveillance aircraft – Lockheed P-3 Orion. The Japanese Navy has the second best anti-submarine capability in the world, only behind the U.S Navy. Therefore, the JMSDF is capable to operate anti-submarine operations between 300 nautical miles to 1000 nautical miles around Japan.
The size of Japanese Navy is much smaller than Chinese Navy, but the advanced level and overall operational capability are better than China. We can also see the Sino-Japanese naval gap from the numbers of large military equipment. The Japanese navy now has 28 5000 tons of large warship, but China only has 13 ships of more than 5000 tons, less than half of Japan. The Japanese missile destroyers are also the best in Asia.
In general, the JMSDF is still the strongest naval force in Asia. China’s naval strength is increasing, but the gap between the two countries still exists. Today’s warfare is not just easily navy fight with navy, but joint operations of land, air, and navy. Thus, I don’t think a war between China and Japan will happen in the near future. War is still the last option for both nations.