Empress Dowager Cixi colluded with foreign forces to suppress the Boxer Rebellion, mainly because the Boxer Rebellion was too powerful to be suppressed by the Qing government alone.

The boxer movement originated after the Sino-Japanese Sino-Japanese War of 1894-1895. At that time, when the Qing Dynasty was defeated, foreign powers began to carve up China, and people's lives were hard. Under such circumstances, the boxer movement gradually rose. At the beginning of the Boxer Rebellion, the slogan was "Anti-Qing Restoration", which broke out all over the country, posing a great threat to the rule of the Qing court. Empress Dowager Cixi was also very alert and sent troops to encircle the Boxer Rebellion, but she never suppressed the Boxer Rebellion.

Because the Boxers wantonly killed foreigners, they also attracted the dissatisfaction of western powers. Western powers accused the Qing court of encirclement and suppression, and proposed to the Qing court to send troops to Beijing to encircle the Boxer Rebellion. Although the Qing court did not agree to encircle the Boxer with the western powers at first, as time went on, the Qing court became more and more tired in fighting the Boxer and had to accept the advice of the western powers and fight the Boxer. Since then, western powers have sent more than 2,000 regular troops to Beijing to encircle the Boxer Rebellion. While the Qing court encircled the Boxer Rebellion, it also mobilized military forces to Beijing to prevent accidents.

Under the double blow of western powers and the Qing court, the Boxer Rebellion was effectively suppressed. However, after the development of the Boxer Rebellion, the attitude of the Qing court towards the Boxer Rebellion changed. For the Qing court, because the Boxers were aimed at foreigners, the Qing court could use them to deal with foreigners. Under this psychological effect, the Qing court decided to win over the Boxer Rebellion. Since then, with the support of the Qing court, the Boxer Rebellion has developed rapidly, and their slogan has also become "Help the Qing Dynasty to destroy the foreign countries". Soon after, the Qing court declared war on foreign countries. Because of the backwardness of weapons and equipment, the Qing court was defeated in the war with the great powers, and even Beijing fell into the hands of foreigners. Empress Dowager Cixi had to sign the "Xin Chou Treaty" with foreigners to calm their anger.

In a word, Empress Dowager Cixi colluded with foreign powers to suppress the Boxer Rebellion, mainly because the Boxer Rebellion was powerful and the Qing court could not suppress the Boxer Rebellion at all.