In recent years, early childhood education for sustainability has received increasing attention. However, research on early childhood teachers in relation to this issue remains marginalized. Teachers' environmental attitudes support children's nature play and are strongly associated with sustainability. According to previous studies, environmental knowledge is important to pro-environmental attitudes. This article used a quantitative survey to explore the environmental attitudes of 832 early childhood in-service teachers and determined the relationship between their environmental knowledge and attitudes. The Two Major Environmental Values (2-MEV) scale was adopted to examine the environmental attitudes of the participants, including conservation and utilization. The outcomes showed that the participants had a more positive attitude toward environmental conservation and a less positive attitude toward environmental utilization. Although their environmental knowledge was relatively low, it significantly predicted their environmental attitudes toward both conservation and utilization, but the impacts were minimal. The 2-MEV scale cannot fully resolve controversies regarding the relationship between teachers' environmental knowledge and attitudes. More attention should be given to other aspects of teachers' jobs, such as job satisfaction and culture.