<p>Previous research has indicated a link between harsh parenting and children’s behavioral problems. However, few studies have focused on preschool-aged children and employed large sample sizes to explore the underlying associations between harsh parenting and both internalizing and externalizing behavioral problems. The present study conducted with the parent of 7731 preschool children in China. The findings reveal that harsh parenting is positively associated with both internalizing and externalizing behavioral problems in preschool children, while parent-child relationship quality is negatively associated with these problems. Furthermore, after controlling age, internalizing and externalizing behavioral problems respectively, parent-child relationship quality partially mediates this relationship. Moreover, sex moderates the association between harsh parenting and preschoolers’ externalizing problems, as well as the relationship between parent-child relationship quality and preschoolers’ internalizing problems. These findings contribute to a deeper understanding of the underlying mechanisms linking harsh parenting to behavioral problems in preschool children and provide practical implications for the prevention and reduction of such problems.</p>