During the past decades, a significant number of chiral aggregates have been produced by molecular self assembly. These chiral aggregates are normally powdered, therefore, a chiral material preparation methodology for these chiral aggregates remains challenging. Here, we report a simple but effective method to prepare chiral and transparent composite films by casting chiral aggregate suspensions in a water solution of poly(vinyl alcohol). Interestingly, this simple strategy can broaden the circular dichroism (CD) signal range and modulate the Cotton effect of the composites prepared by two or more chiral aggregates with different Cotton effects and different CD signal wavelength ranges. This strategy can be used for nearly all other powdered chiral aggregates, and transparent composites with good mechanical properties can be used in advanced devices.