The purposes of this research were to develop environmental education learning plans to enhance wetland management in the Northeast of Thailand by using cooperative-based learning for being efficient and effective, to study and compare knowledge about wetland management in the Northeast of Thailand, attitudes and environmental ethics before and after learning of undergraduate students and to compare knowledge, attitudes and environmental ethics of undergraduate students with a different gender. The sample used in the research was 107 undergraduate students selected by purposive sampling in the 1st semester of the academic year 2020. The research tools were learning plans on wetland management in the Northeast of Thailand using cooperative-based learning, a knowledge test on wetland management in the Northeast of Thailand, an attitude test, and an environmental ethics test. The statistics used in the research were frequency, percentage, mean, and standard deviation, including hypothesis testing using Paired t-test and F-test (One-Way ANOVA). The results showed that: the efficiency of the learning plans on wetland management in the Northeast of Thailand using cooperative-based learning was 97.78/92.36 and the effectiveness index (E.I.) was 0.9430, indicating that the student’s learning progress increased by 94.30%. The undergraduate students had an average score of knowledge about wetland management in the Northeast of Thailand, attitudes and environmental ethics in the post-test was higher than the pretest statistical significance (p < .05). There was no difference in the knowledge score of wetland management in the Northeast of Thailand and attitudes of undergraduate students of different gender (p > .05). And there was a statistically significant difference in environmental ethics of undergraduate students of different gender (p < .05). Male’ score of environmental ethics about wetland management in the Northeast of Thailand was higher than females.