Degradation of P-channel MOSFET during off-state stress with ac bias has been experimentally investigated. Sub-threshold leakage increased after off-state with ac bias. It was caused by hot electron injection during off-state. With varying source voltage, the degradation during off-state stress with ac bias was more severe than off-state stress with dc bias. Degradation impact was the same as hot electron induced punch-through (HEIP) during on-state. It was observed that subthreshold leakage current of pMOSFET increased and standby current became serious. Gate length, tap width, doping concentration at source/drain extension, operation temperature and operation frequency, respectively, were evaluated and the degradation modeling has been introduced in our paper.