In this paper we describe the expansion of probabilistic context free grammar for Urdu language, we did some experiments in probabilistic context free grammar for Urdu language, extraction of CFG rules through The Penn Treebank, evaluation of PCFG from CFG. This PCFG is further useful for parsing the Urdu Sentences. The Tree-bank based grammar is the best technique for building up the PCFG for language through some easy and understandable steps as compared to theoretical. A PCFG can be used to estimate a number of useful probabilities concerning a sentence and its parse-tree(s). The resulting Penn Treebank based PCFG is widely used in natural language processing, speech recognition, and integrated spoken language systems as well as in theoretical linguistics.