This study investigates internal conditions of the solar greenhouse dryer with drying agricultural products. The operating conditions inside the solar greenhouse dryer were analysed by ANSYS Fluent software using mathematical models. Additionally, the moist air outside changed according to the climatic conditions of the day. Specifically, moist air enters the dryer through two front doors and exits through three exhaust fans installed in the back, and the flow was considered unstable and tumultuous. Agricultural products inside the solar greenhouse dryer were modelled as a porous material, and the radiation was modelled according to the radiation model. The simulation results show the distribution of temperature and humidity inside the solar drying greenhouse by the influence of heat exchange, turbulent flow, and the process of removing moisture from the drying material to the outside. The simulation results show that indoor drying temperature ranges from 303.15 K to 323.1 K at each time from 7:00 AM to 6:00 PM. The drying house reached its highest temperature at 2:00 PM. Variations of relative humidity in GHSD are between 23.70% and 79.55%. The airflow velocity inside the drying house is almost independent of time and varies based on location.