The mandatory rotation of auditors can guarantee their independence to a certain extent. The social network, however, serves as a challenge to their independence, and meanwhile improves the handover efficiency between the predecessor and the successor auditors. Based on the samples from 2007 to 2019, it is found that the possibility of the successor auditor issuing clean audit opinions increase if they are in the same audit firm. What's more, the audit quality of successor auditors will be better if the auditor rotation happens in the same audit firm. Also, the possibility of financial restatement is lower and the discretionary accruals are lower. However, the audit fee does not reduce significantly. Compared with the rotation of signature auditors between different firms, the rotation happening in the same firm between auditors are easier in information sharing and communication, which helps to improve the audit quality of the successor auditor compared with the former ones.