This study examined the serial mediating effects of negative parenting and children's mastery motivation on the relationship between family socioeconomic status (SES) and internalizing and externalizing problem behaviors in Chinese preschoolers. A sample of 669 Chinese children between 3 and 6 years (M[subscript age] = 4.83, SD[subscript age] = 0.87, 50.4% girls) was recruited from 12 public kindergartens in a coastal city in southeastern China based on a stratified random sampling procedure. Their parents completed the Multidimensional Assessment of Parenting Scale (MAPS), Dimensions of Mastery Questionnaire for Preschool Children (DMQ 18), and Children's Problem Behaviors Scale (CPBS). Research Findings: (1) family SES was significantly related to reduced negative parenting and children's problem behaviors as well as increased children's mastery motivation; (2) family SES affected children's problem behaviors indirectly through the single mediating path of negative parenting and the single mediating path of children's mastery motivation; and (3) negative parenting and children's mastery motivation were identified the serial mediators between family SES and children's problem behaviors. Practice or Policy: This study has demonstrated how family SES would interact with negative parenting practices concerning early childhood development. The findings also indicated that strategies that assist parents in adopting positive parenting practices or facilitate the development of mastery motivation in children might reduce the occurrence of children's problem behaviors.