Marriage is a relationship between a man and a woman and that will remain Beijing's legal position, a parliament spokesman said on Wednesday, ruling out any changes after self-governing Taiwan passed a law to legalise same-sex marriages in May.
Taiwan's equality bill was passed after years of heated debate that divided the island, which Beijing claims as its own.
There are thriving gay scenes in mainland China's major cities, but there has been little sign the ruling Communist Party will legalise same-sex unions.
Asked if China would legalise same-sex marriage, Zang Tiewei, spokesman for parliament's legal affairs commission, said Chinese law only allowed for marriage between one man and one woman.
"This rule suits our country's national condition and historical and cultural traditions," Zang said. "As far as I know, the vast majority of countries in the world do not recognise the legalisation of same-sex marriage."
In recent years, individual mainland legislators have occasionally proposed measures during the annual meeting of the largely rubber-stamp parliament each March to allow same-sex couples to marry, without success.
There are no laws against same-sex relations on the mainland and, despite growing awareness of lesbian, gay, bisexual and transgender (LGBT) issues, the community has been the target of censors in recent months, fuelling fears of growing intolerance.
Equality campaigners have asked people in China to propose amendments to a draft civil code en masse, although they admitted they saw little chance of success. The parts of the code relating to marriage were expected to pass into law next year.
The code makes changes on issues such as sexual harassment, divorce and family planning, but does not further the rights of the LGBT community, drafts published by parliament showed.
Zang said the marriage section of the draft civil code maintained the bond as one between a man and a woman.
Gay rights campaigner Sun Wenlin said he was disappointed by the comments, but not surprised.
"I feel that my partner and I are sacrificing our happiness for the country's legal system," said Sun, who three years ago lost an application to legally marry his partner in a Chinese court case.
"They are undermining our life plan of choosing to marry the person we love," he said. "I feel I am being excluded, and am absolutely not a consideration for policymakers."