As a spectrum efficient multi-carrier modulation scheme, filter-bank based orthogonal frequency division multiplexing techniques using offset quadrature amplitude modulation (OFDM/OQAM) are investigated for future wireless communication systems, where a low-sidelobe spectrum is achieved by band-limiting each subcarrier while keeping their orthogonality. One of the technical issues in OFDM/OQAM is the suppression of the peak-to-average power ratio (PAPR). Since existing PAPR reduction schemes for traditional OFDM are not straightforwardly applicable to OFDM/OQAM systems, PAPR suppression for OFDM/OQAM is still a challenging issue. This paper proposes a partial scrambling overlapped selected mapping (PS-OSLM) technique for OFDM/OQAM systems, where a partial scrambling technique is applied to an overlapped SLM scheme which selects the best candidate sequence among possible overlapped candidate sequences so as to minimize the PAPR. It is verified by simulation that the proposed PS-OSLM effectively reduce PAPR of OFDM/OQAM signal without explicit side information while improving bit error rate (BER) performance compared with conventional schemes.