This study aimed to: 1) develop lesson plans on Brain-Based Learning with Mnemonics techniques to develop English reading skills on the topic of festivals and celebrations for Prathomsuksa 3 students at criteria at 80/80, 2) study the effectiveness index of Brain-Based Learning with Mnemonics techniques, 3) compare English reading skills between before and after of the students by Brain-Based Learning with Mnemonics techniques, and 4) study the satisfaction towards learning outcomes through Brain- Based Learning with Mnemonics techniques of Prathomsuksa 3 students. The target groups used in this study were the 21 Prathomsuksa 3 students who studied in the second semester of the academic year 2019, Choomchon Banhuailau School, Ban Moung District, Sakon Nakhon Province. The research instruments used in the study consisted of 1) the 4 lesson plans by using Brain-Based Learning with Mnemonics techniques to develop English reading skills, 2) English reading skills test before and after learning, and 3) the satisfaction evaluation from Brain-Based Learning with Mnemonics techniques. Data analyzing by percentage, standard deviation Index of Effectiveness, and t-test was used to test the hypothesis. The research results: 1. The efficacy of lesson plans on Brain-Based Learning with Mnemonics techniques to develop English reading skills on the topic of festivals and celebrations for Prathomsuksa 3 students, from the test during the whole course (E1) and the efficacy of the results (E2) after the class E1/E2 was the level of 81.54 / 91.90. It was higher than the criteria set 80/80. 2. The effectiveness index of Brain-Based Learning with Mnemonics techniques, the overall effectiveness of learning (E.I.) was 0.5612, indicating that Prathomsuksa 3 students knowledge increased to 56.12 percent. 3. The English reading skills of the students after learning by Brain-Based Learning with Mnemonics techniques showed that the test scores before studying was ( =20.61, S.D.= 7.07), post-tests scores was ( =29.09, S.D.= 7.52), indicating that overall, students were higher than before learning. The statistically significant was differences at the .01 level. 4. The satisfaction of the Prathomsuksa 3 students towards Brain Based Learning with Mnemonics techniques to develop English reading skills on the topic of festivals and celebrations was at the highest level.