For 1.27nm thick gate oxide p-channel MOSFETs , the hole mobility booster by the means of process strained silicon (PPS) technique is applied. With the noise measurement, we can extract the trap density Nt and scattering factor α in STI compressive stress PMOSFETs. Specially, We characterize the 1/f noise power spectra density (PSD) of the drain current both in the channel width (W) and the channel length direction. In the channel length direction, the experiment results show that the STI induced stress can provide more interface trap density. However, in the channel width direction, the main decrease of the average trap density comes from the edge structure. The I-V measurement can also give us that the information the stress on narrow device is not the only reason for mobility change. With the combination of the Noise and I-V measurements, the inverse narrow channel effect may provide a appropriate interpretations to both experimental result.