Increase in traffic volume and load on highway bridges requires replacement of the bridge superstructure or adoption of a structural strengthening system. Strengthening of existing prestressed concrete bridges with conventional construction materials results in an increase in dead load. In addition, it may also result in decrease in bridge clearance. The use of Carbon fiber reinforced polymer (CFRP) composites is considered a practical alternative for flexural strengthening of prestressed concrete bridge girders. However, the effectiveness of the CFRP depends on several factors, which have not been quantified well. AASHTO type II prestressed girder is one of the most popular girders carrying highway bridge decks, in the U.S.A. This paper presents a finite element analysis of CFRP strengthened AASHTO type II prestressed girder. Several variables were investigated: concrete strength, ratio of prestressing strands, and ratio of CFRP composites. For CFRP strengthened PC girders, the results of this investigation suggest that for the same amount of CFRP, the lower the ratio of prestressing strands, the higher the percentage increase in flexural strength. In addition, strengthened girders exhibit comparable ductility as un-strengthened PC girders.