This study investigates the effect of chapped strand glass fiber on fracture behavior of polymer composites. Chopped strand glass fiber reinforced particle-filled polymer composite beams with varying notch-to-depth ratios and different volume fractions of glass fibers were studied in Mode I fracture using three-point bending tests. Effects of polyester resin content and glass fiber content on fracture behavior was also studied. Polyester resin contents were used 13.00%%, 14.75%, 16.50%, 18.00% and 19.50%, and glass fiber contents were 1% and 1.5% of the total weight of the polymer composite system. Flexural strength of the polymer composite increases with an increase in polyester and fiber content. The critical stress intensity factor was determined by using several methods such as initial notch depth method, compliance method and J-integral method.