The Sri Lankan Green Pit Viper (GPV), Peltopelor trigonocephalus (Donndorff, 1798), is a medically important snake species in Sri Lanka. It is a high-potential venomous species endemic to Sri Lanka. Data on sex-specific morphological differences are scarce. A visual encounter survey was utilized to observe GPV and obtain their morphometric measurements. The morphometric data was analyzed using Principal Component Analysis (PCA), which identified three distinct clusters that were divided into the three maturity phases of adult, sub-adult and juvenile. Positive values for all parameters were represented on the Principal 1 (PC1) axis, which showed a high variance percentage (90.1%) and related proportional relationships between the values, showing that when one parameter increases, the other parameters follow suit. The morphometric parameter with the greatest Dim 1 value (0.979) was found as total length (TL), which had significant impacts on the PC1 axis. TL was used as the primary measurement to visually categorize maturity stages. Adult females had the highest values for all of the variables evaluated. According to the findings of this study, the maturity stages of GPV species were successfully categorized using morphometric data.