This paper explores the addition of Parallel Interference Cancellation (PIC) to the Frequency Domain Equalization (FDE) for downlink Zero padding CDMA (ZP-CDMA) system . FDE for ZP-CDMA is a novel type of single carrier that have two main advantages over Orthogonal Frequency Division Multiplexing (OFDM), namely, lower peak to average ratio and reduced sensitivity to carrier frequency error. PIC method is an effective method to suppress MAI and improve the uplink capacity for DS/CDMA system. Recently, it has been viable for the downlink and terminal implementations. In this paper, We first investigate the impact of the decision functions on the performance of PIC for downlink ZP-CDMA .We then develop an efficient algorithm based on Frequency domain Regularized Zero Forcing Equalizer and unit clipper decision PIC (FDE-RZF-CPIC) suitable for downlink ZP-CDMA cellular systems. Results indicate that FDE-RZF-CPIC provides better performance than conventional RAKE receiver , FDE-RZF equalizer and the RAKE receiver with PIC.