Brother and sister of different parents are generally not allowed to marry. Except that both parties are remarried family members of both parents, and there is no blood relationship within three generations. According to relevant laws and regulations in China, marriage is prohibited for direct relatives by blood or collateral relatives within three generations.
 Legal basis
 Article 1046 of the Civil Code of the People's Republic of China [Voluntary Marriage] Marriage shall be completely voluntary between men and women. Neither party is allowed to force the other party, nor is any organization or individual allowed to interfere.
 Article 1047 [Legal age for marriage] of the Civil Code of the People's Republic of China, the age for marriage shall not be earlier than 22 for men and 20 for women.
 Article 1048 of the Civil Code of the People's Republic of China [Circumstances under which marriage is prohibited] Marriage is prohibited for direct relatives by blood or collateral relatives by blood within three generations.
 Article 1049 [Marriage registration] of the Civil Code of the People's Republic of China requires both men and women to apply for marriage registration in person at the marriage registration office. Those who meet the provisions of this Law shall be registered and issued marriage certificates. The marriage relationship is established when the marriage registration is completed. If no marriage registration is handled, it shall be re registered.