Environment Education is a priority for sustainable development at primary school level in line with UNESCO to produce citizens with sustainable lifestyles. This study aims to identify the level of knowledge, attitude and practice/behaviour among primary school teachers regarding the environmental education for sustainable development. It then also analysed the relationship between the level of knowledge, attitude and practice/behavior of sustainable development. Data were obtained quantitatively through a questionnaire survey where 300 teachers were randomly selected to be involved in this survey. The result showed that the level of knowledge of sustainable development among primary school teachers is high with the mean value of 3.80. The level of attitude sustainable development is also at a high level with the mean at 3.70 meanwhile the level of practice/behavior, sustainable development at moderate level with the mean of 3.25. This study also revealed that there is a strong and significant relationship between the level of knowledge and attitude of sustainable development primary school teachers with r -value at 0.765. There is a weak correlation between the level of teacher’s attitude and their practice/behavior with r -value at 0.455. It clearly showed that higher knowledge influences the attitudes of primary school teachers for sustainable development. At the other point, higher knowledge and attitude is not a guarantee towards positive practice/behavior for sustainable development among primary school teachers. This situation needs improvement and an effective way to produce today's generation that loves their environment and nature. Teachers as an educator became a front liner group for making sure environment education is successful at primary school level.