The finite positive realness property of singularly perturbed systems is studied based on generalized Kalman-
Yakubovic-Popov (KYP) lemma approach. According to the two-frequency scale property of singularly perturbed
systems, namely the low(slow) frequency and high (fast) frequency, generalized KYP lemma is applied to the reduced-order subsystems of singularly perturbed systems in the corresponding frequency domain. Then sufficient and necessary conditions are derived to make sure that the subsystems are finite frequency positive realness (FFPR). Furthermore, it is proved that the singularly perturbed systems are FFPR under certain conditions.