Using transfer matrix and equivalent principle, the Tamm state on the surface of the symmetric photonic crystal was investigated in the new point of energy levels. The result shows that when the symmetric system is an infinite periodic structures for photonic crystal, there is impedance mismatch between incident medium and photonic crystal, thus the optical Tamm state on the surface doesn′t exist. When the photonic crystals is truncated to finite period structure, it supports the appearance of the optical Tamm state on the surface, and the doubly degenerated energy level of TE and TM polarization appears in the energy band. In optical off-axis transmission, the optical Tamm state form the passband edge non-degenerated energy which is restricted on on the surface of photonic crystal. When the truncation parameter is matched with the high refractive index of outmost layer, it is easy to form a strong optical Tamm state. But when it is matched with the lower refractive index of outmost layer, it is difficult to realize the surface state. When the surface state of photonic crystal is excited by the ATR total reflection technique, the coupled resonance absorption can be observed. The properties of optical Tamm state on the surface of photonic crystal can provide guidance for research and design of optical waveguide or surface wave sensor.