To understand better the issue at hands, it's fundamental to know the point of view of China on homosexuality.
In the history of China, homosexuality was never directly criminalized, contrary to Singapore. In 2001, the Chinese Society of Psychiatry commissioned a working group to study the psychology of gays and lesbians, and research findings ultimately led to the removal of homosexuality and bisexuality from the official list of mental disorders in the Chinese Classification of Medical Disorders.
However, culturally, it's frowned upon. Indeed, China's first and foremost value is family. A traditional family involves a heterosexual marriage. Though, the society is changing due to the younger generations, who have more freedom to live their personal lives as they wish.
Religions are, of course, against homosexuality, which is a huge factor in the acceptation of LGBT rights.