The photonic spin Hall effect (SHE) has great potential in precision metrology due to its unique spin modulation characteristics. To improve its potential, the effective enhancement of detection precision has become an important issue. In this work, we theoretically and experimentally demonstrate the optimal weak measurement (optimal overlap of pre-selected and post-selected states) with arbitrary linear polarization incidence for both amplified transverse and in-plane shift. Also, based on photonic SHE, a method for arbitrary linear polarization angle detection is then proposed experimentally with a detection accuracy of 0.04 degree. It can provide a guidance for the weak measurement and enlarge the potential application of photonic SHE in field of precision measurement.