No. China is not considered part of Southeast Asia.
The countries usually included are Burma (Myanmar), Thailand, Cambodia, Laos, Vietnam, and Malaysia, and the island nations that (like part of Malaysia) lie in the seas to the south and east. These include Brunei, East Timor, Indonesia, the Philippines, and Singapore.
The country of Belize is southeast of the People's Republic of China. The two countries are separated by the Pacific Ocean.
The Ocean is the Pacific Ocean, however the bit next to China is called the South China Sea.
China is located in Southeast Asia. China is along the coast of the Pacific Ocean. The World Atlas shows China located in the Middle Eastern part of the world.
China dominates the Pacific Asia region economically.
southern China and South Asia
to attract foreign investment and technology to China
mountainous region, rivers, plains
The emerging economic region of China is Guangzhou. Guangzhou enjoys proximity to a port and it has a number of industrial zones within it.
Japan and China
At its height during World War II, the Japanese Empire included territories in East Asia and the Pacific, covering areas such as Korea, Taiwan, parts of China, Southeast Asia, and various Pacific islands. The empire reached its peak in the early 1940s before its eventual defeat in 1945.
Native to China and Japan but also found in tropical regions of Southeast Asia, the Pacific islands and South Africa.
Russia (Battle of Nomonhan 1939), China (Manchuria), Southeast Asia, the South Pacific, and parts of Alaska.