Two-chamber and three-chamber peristaltic micropumps with straight channels or tapered channels are fabricated by UV photolithography. Piezoelectric buzzers are chosen as actuation elements because they are cheap and have high actuation amplitude. A negative photoresistive material, SU8-25, is used as a structure material, and PDMS is chosen to bond different parts of the micropump. The effects of working phases and channel geometries are investigated and the performance of two-chamber and three-chamber micropumps is compared. The results indicate that three-chamber micropumps have better flow rates than two-chamber counterparts. For three-chamber micropumps, four-working phases have the best flow rate, six-working phased are the second, and three-working phases are the last. The channel length may have no clear effect on the flow rate, while the channel width and the angle of nozzle/diffuser have evident effects on the flow rates.