Fragment based drug discovery (FBDD) by the aid of different modelling techniques have been emerged as a key drug discovery tool in the area of pharmaceutical science and technology . The merits of employing these methods, in place of other conventional molecular modelling techniques, endorsed clear detection of the possible structural fragments present in diverse set of investigated compounds and can create alternate possibilities of lead optimization in drug discovery . In this work, two fragment identification tools namely SARpy and Laplacian-corrected Bayesian analysis were used for previous SARS-CoV PLpro and 3CLpro protease inhibitors . A robust and predictive SARpy based fragments identification was performed which have been validated further by Laplacian-corrected Bayesian model . These comprehensive approaches have advantages since fragments are straight forward to interpret . Moreover, distinguishing the key molecular features (with respect to ECFP_6 fingerprint) revealed good or bad influences for the SARS-CoV protease inhibitory activities . Furthermore, the identified fragments could be implemented in the medicinal chemistry endeavors of COVID-19 drug discovery.