Most of longan productions in Thailand encounter inconsistent output. The discovery of the off-season longan production technology, by using the chlorate compound, results in the changes in production system and development of the longan production in Thailand. This study aimed to explore the effects of the off-season longan production technology. Its objectives were to study the efficiency of the inputs of the in-season longan production and the off-season longan production, and to analyze t he economic impact of off-season longan production, by using the Transcendental Logarithmic Function cost function. From the research, it can be concluded that both the in-season longan production and the off-season longan production are at increasing returns to scale. When compared with the technical efficiency, the off-season longan production is more efficient than the in-season longan production, it implies that the off-season longan production increases output and efficiency. For the study of the economic impact of off-season longan production by comparing between producer surplus of the in-season longan production and the off-season longan production, results that the farmers who use the off-season longan production technology have more producer surplus than those who use the in-season longan production technology. In addition, they have better social welfare as well. However, this study aims to explore the impact of using the off-season longan production technology by excluding its future impact, which is the interesting issue to be further studied.
