Purpose: Although the number of school-based education programs for child sexual abuse (CSA) prevention has recently increased in China, little is known about their effectiveness. This meta-analysis aimed to examine the effectiveness of school-based CSA prevention programs on improving children’s knowledge and skills, which can prevent them from being sexually abused. Method: Systematic searches were conducted based on five English-language databases (PubMed, Web of Science, ScienceDirect, MEDLINE, and PsycINFO) and three Chinese databases (CNKI, Wan Fang Data, and CQVIP). Seven studies with 2,593 participants finally met the quality criteria of this review, and the meta-analysis was conducted using a random effect model. Results: The overall effect sizes of school-based CSA prevention education showed a significant improvement in children’s knowledge ( d = 2.53, 95% CI [2.03, 3.04]) and skills ( d = 2.00, 95% CI [1.39, 2.60]). Programs instructed by researchers were more effective than those instructed by teachers, and preschoolers had a larger increase in both knowledge and skills than elementary and middle school students. Discussion: This study provides empirical evidence for further implementation of school-based CSA prevention programs, especially under the guidance of experienced researchers and conducted for students at an early age.