The article analyzes several typical poems in Bac Hanh Tap Luc (Travels to the North) by eminent poet Nguyen Du criticizing ethnic discrimination of Chinese feudalism. According to the author, about 80 percent of the poems composed during Nguyen Du's travels, directly or indirectly, expressed the thought of vigilance over China with the inclination of criticizing and ironizing ethnic discrimination at various levels. So, it can be said that this is a poetic diary which is worth as much as a poetical "diplomatic memorandum" or a "white paper" about China and its people. In those poems, the true face of Chinese feudalism was exposed: Chinese people were exploited and doomed, and neighboring small countries were discriminated and invaded, causing sufferings to other peoples. Through Nguyen'Du's critical thinking, the authors can see that a thought of "desinicization" was shown.