Position Sensitive Detector(PSD) features high position resolution and the setup of position displacement measurement system is simplified. The performance of measurement circuit is the key factor for the application of PSD. Some results are obtained by the way of analyzing the equivalent noise of measurement circuit. The circuit noise is one of the most important factors which will lower the position resolution. For one dimensional PSD device S3932, the position resolution of 1μm can be achieved if the photocurrent of the device is above 7μA.