A reference check is a selection tool that used quite often by employers for identifying their potential employees. It has often been introduced in Human Resource Management textbooks, management articles, or consulting companies¡¦ training courses. However, when compared with other selection tools, a reference check obviously lacks both systematic researches and empirical studies to prove its credibility. This study is to gain an understanding as to the reason why an employer undertakes a reference check; how employers undertake a reference check and the overall procedure; and the influence and beneficial results of reference check. And I interviewed 12 HR professionals to collect their personal experiences about reference check. The results show that a reference check is one of the guarantee mechanisms for employers for not hiring an unqualified candidate. Employers take references from referees regarding their comments on applicants, who have already passed several selection processes and selection tools, in order to filter out the applicants who have some unfound problems in precious selection processes or tools. With regards to the hired applicants, employers could understand more about their personalities, strengths and weaknesses from the reference check results. Normally applicants would not list referees with whom they have had bad relations, so employers might undertake an unofficial reference check through their own personal network to collect information that will not be biased by good relations between applicant and referees. The results also show that some applicants may overestimate their good relationships with their referees, and list the referees who give their negative evaluations on applicants. In general, the referees who are familiar with the applicant, and who are willing to provide a reference along with those who undertake the reference check in a very sensitive manner, are the two key factors that make the reference check work well. Key word: Reference check, Selection