In phase sensitive OFDR systems, tuning scanning nonlinearity and phase demodulation algorithm are the key factors that affect the system performance. By adopting improved nonlinear phase compensation algorithm based on polynomial regression algorithm (PRA) and phase demodulation algorithm based on arctangent function and differential-self-multiplying (ARC-DSM), we demonstrate a scheme of phase sensitive OFDR-based distributed optical fiber strain sensing system with high precision and spatial resolution.