The present study aimed to investigate the status and relationships between family support for infant and toddler care and parenting stress, and to explore differences related to the number of children in the families. We conducted a survey among 13,390 Chinese parents who were randomly sampled from six provinces of China. Descriptive analysis, multivariate analysis of variance, and regression analysis indicated that (1) current family support for infant and toddler care in China is insufficient; (2) most Chinese parents reported moderate parenting stress, with the highest scores given for parental distress, followed by difficult child, and parent–child dysfunctional interaction; (3) the larger the number of children in the family, the less the family support for infant and toddler care, the greater the parenting stress; (4) there was a difference between the effects of family support for infant and toddler care on relieving parenting stress among families with different numbers of children. These findings indicate that different types of family support for infant and toddler care should be provided for families with different numbers of children, to ease parenting stress and promote the implementation of the government’s current fertility policy.