Doctor Who proved to be a challenge for the Chinese government which eventually decided to ban it. The reason for that harsh decision was the fact that the series inspired Chinese people to oppose the government and demand more human rights. By describing past events, Doctor Who actually tries to draw moral to present issues and this is not something well taken by most Chinese officials.
The official explanation is that the sci-fi series distract Chinese citizens from reality as they imagine themselves in alternate realities. The results are that they do not work, become unproductive and a burden for the society. What is even worse, they oppose the government which took a strong position against the depiction of time travel.
Such behavior is not a new thing in human history as science fiction books promoting progressive ideas and new social order have been opposed, censored and even burned during different periods of human history. So, it is, undoubtedly, a powerful tool which could cause problems for the current government in China which cannot control people’s fantasies forever.