Masin is a Sumbawa sauce made from fermented rebon shrimp. That has several shortcomings, such as non-uniform time for masin fermentation. Therefore, the design of FERMAS-KECE, a masin fermenter equipped with a temperature control system, is carried out to optimize the fermentation process. This study aims to determine the thermal distribution controlled by the heater position and velocity of the fan using the computational fluid dynamic (CFD) method with Ansys software. CFD simulation is done on Ansys 2022 R2 student version. The variables studied were fan speed variables 2m/s, 1,5m/s, and 1m/s. Variable heater position one (bottom), position two (middle), and position three (upper and lower) are the heater position on the Fermenter. The simulation results of the heat distribution with fan speed 2m/s at positions one, two and three, namely 331,5K, 332,7K, and 332,2K, thermal distribution with fan speed 1.5m/s at positions one, two and three are 329,6K, 330,5K, and 330,2K. Thermal distribution with fan speed 1m/s at positions one, two and three are 326,3K, 326,9K, and 326,7K. The simulation results show that the CFD simulation's thermal distribution at position two with a fan speed of 2 m/s is 332,7K and has uniform color thermal distribution contours. We hope that the placement of the heater and fan speed on the Fermenter can optimize the masin fermentation process.