Abstract 【Aim】 The semiectoparasitoid Sclerodermus guani tends to parasitize solitary wood-boring insects in concealed habitat (trunk or seed). Effective mating tactics are critical for population colonization and expansion of S. guani. This study aims to explore the mating behavior of S. guani and to unveil its mating tactics. 【Methods】 The mating process of both male and female adults of S. guani (♀∶♂=1∶1) was recorded with dissecting microscope, video camera and insect behavior tracker in the laboratory, and the differences in behavior performance, time allocation and speed of mating between female and male adults during the whole mating process were compared. 【Results】 The mating process of S. guani adults can be divided into three phases, i.e., pre-copulation, copulation and post-copulation, and the mating behavior shows a series of characteristic procedures including antennal drumming, mounting females, walking on the back of females, probing and copulation. In the pre-copulation phase, males walk around quickly, touch and drum females by antennae, and touch females by mouthpart. After mounting females, males walk on the back of females and still keep tapping females with antennae or touching with mouthpart. Females always keep a stereotypical posture of being stationary with head down. The total lasting time for the pre-copulation phase was about 653.617±54.160 s (mean±SE). During copulation, males insert their aedeagi, their forelegs incline to the front-end of abdomens of females at an angle of 45°, while their mid legs and hind legs hold the abdomens of females, and the mating duration was about 43.567±7.120 s. In the post-copulation phase, males signal the end of copulation by dismounting and moving away from the copulation site while females keep immobile for approximately 172 s. Both male and female adults exhibit multiple mating behaviors in the whole mating process. With the increasing of mating frequency, the mating duration increases at first and then decreases. In the whole mating process, the mating behavior of male and female adults is first decelerated and then accelerated. The mean mating velocities of S. guani in precopulation, copulation and post-copulation were 3.111, 0.595 and 1.016 cm/s for female adults and 2.754, 0.895 and 1.314 cm/s for male adults, respectively. 【Conclusion】 Male adults of S. guani behave actively during the mating process, suggesting that they play leading roles in spouse search, recognition and selection. The results of this study provide the theoretical basis for artificial reproduction, release and population rejuvenation of S. guani in the field.