This present disclosure discloses techniques for establishing social network service (SNS) relationship. According to the techniques, online payment information of the first user and/or the second user are obtained from the database of the online transaction platform. Using this online payment information, it is determined whether the first user and the second user know each other. If they do, a message to establish an SNS relationship establishment is sent to the first user. The message contains personal information of the second user and allows the first user to decide whether to establish the relationship. The techniques therefore improve security and success rates in establishing SNS relationships.