The Hundred Flowers campaign was set up by Mao the nature was to address mainly the educated classes and to allow them to comment on the government's policies. He and his government knew that the educated mainly disagreed with the policies, but thought that they could no longer deny that China had advanced since the Nationalist regime. However they were to be disappointed with the resulting torrent of criticism from the public, that not only disagreed on the policies but the social structure as well, after which Mao stopped this and arrested many of the people that complained.
The Hundred Flowers campaign was done for either one of two reasons, Mao afterwards called the people that complained R ightists, and said that between 1 and 10 percent of China were, and that they would be arrested, possible killed or jailed, and that the Hundred Flowers campaign was only a way for him to "entice snakes out of their lairs".
However, it could also be that Mao did want to originally use the criticism to improve China as he had once said, and only after fearing a revolution did he stop it. We can never know for sure as it was never specified in any diary or journal that he kept, and he is now dead, however we do know that Mao had previously dislike the educated "intellectuals" who had always rebelled his government.
Mao launched the Cultural Revolution because power was slipping from his hands, the old nationalist ideas were being recreated, his original communism turning into a more capitalist idea, he wanted back his power, and to give the young "revolutionary experience".
Mao put his ideas to the young, and easily corruptible minds and gave them a Red Book of all his ideas, and created a Cult...