This paper presents an assessment of insole based gait feature variation with progression of Parkinson's disease (PD). Gait and postural disturbances are the common cause of disability and impairment for patients with PD. Variation in gait features can serve as important bio-markers to identify severity of PD. Insole based gait features like stride, swing time, maximum vertical ground reaction force (VGRF) and Centre of Pressure (CoP) variation have been evaluated from PD gait database for a set of PD patients and age matched control group. PD group has been further divided in `Mild' and `Moderate' group-based on severity of PD. Inter group segregation has been derived using three conventional PD progression scales named Hoehn-Yahr, Unified Parkinson's Disease Rating Scale (UPDRS) and Timed Up and Go test (TUG). Gait features were re-evaluated for each group and further analysed to understand the effect and variation of the gait features with proaression of the disease.