School tie as a social relationship has always been a focus of academic attention in promoting information exchange among participants in the capital market. Using the earnings forecast data released by China’s security analysts from 2011 to 2021, this paper finds that if the analyst has a school tie with the firm’s auditor, the analyst’s earnings forecast for the company is more accurate, and with the emergence and rupture of the school tie between analysts and auditors, the accuracy of earnings forecast has improved and decreased. Again, for the same analyst, when he/she has school ties with the firm’s auditor, the accuracy of earnings forecast of the firm is higher than when he/she has no school ties with the firm’s auditor. The analyst who has a school tie with the auditor is more likely to visit the firm during the period when the related auditor conducts annual financial statement audit in the firm. In addition, if the analyst has a school tie with firm’s auditor, his/her earnings forecast revisions cause stronger stock price reaction than the analyst who has no school ties with firm’s auditor. Finally, alumni relationship with analysts can help auditors improve audit quality and mitigate professional risks. These findings indicate that the school tie promotes the information communication between analysts and auditors, and improves the accuracy of analysts earnings forecast.