The purposes of this research were to study and compare knowledge about soil, water and forests conservation, environmental ethics and environmental volunteers using the environmental education training course on the concept of The King Rama ? of Thailand in soil, water and forest conservation before and after training of students having different genders and Grade Point Average (GPA). There were two sample used this research: one involved in the curriculum development consisting of 94 students in Environmental Education, Faculty of Environment and Resource Studies Mahasarakham University enrolled in the course Environmental Education Training Curriculum in the first semester of the academic year 2018, and the other composed of 67 first-year students in Environmental Studies who were enrolled in the course Environmental Education in the second semester of the academic year 2018. Both groups were selected through the purposive sampling. The research instruments were Environmental Education Training Course in soil, water and forest conservation on the concept of The King Rama ? of Thailand, knowledge test about soil, water and forest conservation, environmental ethics test and environmental volunteers test. The statistics used in the research were frequency, percentage, mean, standard deviation, including hypothesis testing using t-test, F-test One-Way MANOVA, One-Way MANCOVA, and Univariate Test. The results showed that: (1) The students' average score of knowledge about soil, water and forest conservation on the concept of The King Rama ? of Thailand, environmental ethics, and environmental volunteers in the posttest was higher than the pretest statistical significance (p< 0.05); (2) There was significant different of average score of knowledge about soil, water and forest conservation on the concept of The King Rama ? science of Thailand, environmental ethics, and environmental volunteers between students with different gender statistical (p< 0.05); and (3) There was significant different of average score of knowledge about soil, water and forest conservation on the concept of The King Rama ? of Thailand, environmental ethics, and environmental volunteers between students with different Grade Point Average (GPA) statistical (p< 0.05).