There were mixed results about the relationship between parental educational aspirations and students' academic achievement. Parental educational aspirations, expectations and aspiration-expectation gap have internal association. To gain deeper insights about them, the present study aimed to explore the effects of parental educational aspirations, expectations and their gap on students' academic achievement, controlling potential confounding factors. A total of 3448 students (52.78% boys, M[subscript age] = 12.53 years) from 79 schools were selected using the whole class sampling method. Hierarchical linear models were employed for data analysis. The results showed an inverted U-shaped relationship between parental educational aspirations and academic achievement. Students' academic achievement had a positive linear relationship with parental educational expectations, and a negative linear relationship with the aspiration-expectation gap. These findings indicate that parental educational aspirations are positively associated with academic achievement, but this relationship turns negative when parents aspire for their children to achieve beyond a bachelor degree. The current study provides new understandings regarding the relations among parental educational aspirations, expectations and aspiration-expectation gap, and their effects on children's academic achievement.