Abstract: Jiùshi is a frequently used discourse marker in Mandarin conversation. While existing studies have noted its occurrence in conversational repair, they have largely overlooked its nuanced interactional functions. To address this gap, the current study employs conversation analysis as its research methodology to examine the use of jiùshi in naturally occurring interactions. Data analyses indicate that jiùshi consistently functions as a repair preface in same-turn self-initiated self-repair sequence, preceding the repair solution, marking the occurrence of repair, and projecting the nature of the upcoming repair. Jiùshi-prefaced self-repair enhances the information granularity or refines the formulation of the trouble source.