Abstract The "Evaluation of CropSyst model for rainfed groundnut under middle Gujarat agroclimatic zone" research used a randomised block design (factorial) with four replications to conduct field tests during the kharif seasons of 2019 and 2020. The goals of this research were to (1) use CropSyst to examine the water productivity of kharif groundnut and (2) calibrate CropSyst for groundnut cultivars under rainfed environment. Twenty or fewer days following the start of the monsoon planting season resulted in the lowest pod yield (1614 kg ha-1) and above ground biomass output (4463 kg ha-1). The commencement of monsoon planting resulted in the greatest pod yield (1862 kg ha-1) and above ground biomass output (4765 kg ha-1). Groundnuts sown at the start of the monsoon season had a much higher pod yield (2019 kg ha-1) and above-ground biomass output (5257 kg ha-).