This study analyzed the effect of primary and secondary school students’ on-campus out-of-school-hours (OSH) tutoring participation on private tutoring participation using the two-level Bernoulli model based on the China Family Panel Studies (CFPS) data in 2018. The results revealed that students’ on-campus OSH tutoring participation did not decrease the likelihood of their private tutoring participation, while low-achieving students or students from disadvantaged family socioeconomic status (SES) were more likely to continue to participate in private tutoring after receiving OSH tutoring. This may be due to the following: Firstly, on-campus OSH tutoring was less targeted and personalized before the implementation of the “double reduction” policy; secondly, private tutoring institutions conducted misleading marketing and offered private tutoring in the time for on-campus OSH tutoring; and thirdly, students with disadvantaged family SES had fewer opportunities to receive high-quality OSH tutoring. Therefore, it is suggested that concerted efforts be made to provide more targeted and personalized on-campus OSH tutoring and prohibit academic private tutoring institutions from entering campuses. Additionally, it is necessary to enrich the supply of OSH service resources for interest and quality development, optimize the allocation of on-campus OSH tutoring resources, and facilitate the balanced, quality-oriented development of OSH tutoring among different schools and regions.