1. The objective reason is that the reactionary forces at home and abroad are too strong. The Qing government concentrated the reactionary forces all over the country, including the central and local governments, the army and the Manchu landlords and bureaucrats, pursued the policy of "borrowing teachers to help suppress" and colluded with foreign invaders to suppress the Taiping Heavenly Kingdom uprising. A simple peasant war cannot defeat such a powerful enemy.
2. The subjective reason is that the peasant class leading this movement is not the representative of the new productive forces, and is limited by the class and the times. This is manifested in the following points:
(1) Without the guidance of scientific revolutionary theory, Hong Xiuquan, Yang and other Taiping Heavenly Kingdom leaders could not have put forward a revolutionary program of completely opposing foreign aggression and feudalism in their own countries.
(2) The serious sectarian ideology within the leading group and the resulting struggle for power and profit undermined the unity of the uprising team, greatly weakened its own strength, and did what the enemy wanted to do but could not do.
(3) After the capital Tianjing, the leading group was complacent, greedy for enjoyment, and strictly differentiated grades, which made the Taiping Heavenly Kingdom feudal and seriously divorced from the people, thus gradually losing the support of the people.
(4) Worship of God played an active role in publicizing and organizing the masses in the early days of the Taiping Heavenly Kingdom Movement, but later, Hong Xiuquan, Yang and others used worship of God as a tool to fight for power and profit, which led to a catastrophe of cannibalism and made the masses shake their faith in God.