In 1938, the darkest period in China's Anti-Japanese War, American woman writer Pearl Buck was awarded the Nobel Prize of literature for her notable works providing epic depiction of wartime China, realistic representation of ordinary Chinese people's heroic fighting against fascist Japan, and her great studies of human ideals passing over widely separated racial boundaries. Dragon Seed, one of Pearl Buck's greatest works on China's Anti-Japanese War, has attracted lots of researchers on Pearl Buck from its historical themes to unique narrative techniques, yet few of them have focused on the author's primary emphasis on Chinese grass-roots efforts in Anti-Japanese Resistance. With the help of Wmatrix 3.0 and GraphColl 2.0.0, the present study adopts a corpus-based semantic analysis of Dragon Seed with the comparison to her eight other similar works and reveals that anti-Japanese motivations, battle fields, tactics of Chinese civil forces as well as their considerations of the war contributed to Pearl Buck's great art of portraying China's grass-roots Anti-Japanese Resistance. The results shed light on Pearl Buck and her works on China's Anti-Japanese War.