The government employee surnamed Shi surrendered to the police two hours after stabbing Sun Hengshan, according to the report released by the police of Changchun, capital of Jilin.
Sun died in the hospital about two and half hours after the incident.
Shi said he killed his supervisor for giving him an "incompetent" rating in the 2014 annual work assessment, which led to his subsequent demotion.
Shi and Sun worked for the provincial department responsible of handling cult-related issues in Jilin. Sun headed the office and Shi was his subordinate.
At about two o'clock Friday afternoon, Shi entered Sun's office and used a knife to stab Sun dozens of times before escaping, The Economic Observer reported.
Sun, the former head of Jilin Province's discipline inspection commission, assumed his post at the office of cult related department in November 2017.
Shi is under criminal detention. The case remains under investigation, according to police of Changchun.