China's a big country with lots of climatic zones, so there's no one "look" to it. About a year ago I did some research for Agracier's Hankow map over at AAA and here's what I found:
1) Central China, and presumably coastal China, has/had lots of little villages, each surrounded by a wall and then rice paddies. Upland areas are generally wild or are used to grow other crops, such as tea or fruit. Rice paddies flood during the spring, allowing the farmers to plant rice shoots by hand (that's what's going on in pictures of Southeast Asian farmers knee deep in rice paddies). Later, the water is drained out or evaporates, leaving the paddy dry. By late summer or autumn, certain areas of China, especially badly deforested inland areas, might be dry and dusty.
2) China has always had problems with rivers which flood in the spring (due to rains and runoff from melting snow in the Himalayas). An extensive system of levees was used to protect towns and rice paddies from flood damage. This means that water features can vary widely during the year and areas around rivers often have an "artificial" look to them due to canals, levees, etc.
3) During the Sino-Japanese War and WW2, China had a "drowned earth" policy where they deliberately breached levees in territory lost to the Japanese. Also, the weather was quite wet in some years of the war. This increased flooding and created a lot of backwaters.
Probably the best site for WW2-era maps is here:
http://www.lib.utexas.edu/maps/historical/history_china.htmlYou can get a fairly good sense of the lay of the land from pre-war maps and U.S. Army topographic maps of the period.
More modern maps and satellite views might be alright for ground textures and maps of mountainous or desert areas, but since WW2, and especially since 1980, China's more populated regions have radically changed. For example, in modern times, the city of Hankow no longer exists (or, rather, it has been subsumed into the metropolis of Wuhan).
I guess that you could kludge the Bessarabia or Crimea map into looking like part of the Chinese coast along the South China sea by changing the ground textures and repopulating the towns with East Asian objects. But, many of the hills and mountains in China are much older and more eroded, giving them a craggier appearance, which I'm not sure it's possible to get right in IL2.