From his Confucianist point of view, Ngô Sĩ Liên often made negative comments on historical figures who acted against the rule of Confucianism. For example, despite his obvious successful reign, the Emperor Lê Đại Hành was heavily criticized in "Đại Việt sử ký toàn thư" for his marriage with Dương Vân Nga who was the empress consort of his predecessor. One researcher even speculated that since Ngô Sĩ Liên had a bias against this emperor, he decided to attribute the famous poem "Nam quốc sơn hà" to Lý Thường Kiệt instead of Lê Đại Hành who was considered by several sources the proper author of the "Nam quốc sơn hà". Other decisions of the rulers which did not follow the moral and political code of Confucianism were also criticized by Ngô Sĩ Liên such as the coronation of 6 empresses by Đinh Tiên Hoàng, the marriage of Lê Long Đĩnh with 4 empresses or Lý Thái Tổ's lack of interest in Confucianist classics study. Especially in the case of the Trần Dynasty, Ngô Sĩ Liên always made unfavourable remarks on the marriages between closely related members of the Trần clan. The only short period during the reign of the Trần Dynasty that Ngô Sĩ Liên praised was from the death of Trần Thái Tông in 1277 to the death of Trần Anh Tông in 1320 while the historian denounced many actions of the Trần rulers such as the ruthless purge of Trần Thủ Độ against Lý clan or the controversial marriage between Trần Thái Tông and the Princess Thuận Thiên.