The purpose of this study was to explore Chinese and Australian primary children's conceptual understandings of the Earth. The research was conducted in the interpretive paradigm and was designed to be descriptive with comparative and cross sectional elements. Participants were Year 3 and Year 6 children from three schools in Hunan Province, central south China (n = 38) and Year 3 and Year 6 children from three schools in Western Australia (n = 36). In-depth interviews including drawings were carried out to explore the participants' conceptual understandings of the Earth's shape, gravity, day/night cycle and seasons. The results showed that, regardless of different cultures, children from the same year group constructed similar concepts about the Earth. The Year 3 children were more likely than the Year 6 children to demonstrate intuitive conceptions of a round and flat Earth. The Year 6 children were more likely to demonstrate consistent understandings of a spherical Earth. The findings supported the universality of entrenched presuppositions hypothesis. Cultural mediation was found to have a subtle impact on children's understanding of the Earth. A model of conceptual development is proposed.