  We determine spectral indices of 228 pulsars by using Parkes pulsar data
observed at 1.4 GHz, among which 200 spectra are newly determined. The indices
are distributed in the range from -4.84 to -0.46.Together with known pulsar
spectra from literature, we tried to find clues to the pulsar emission process.
The weak correlations between the spectral index, the spin-down energy loss
rate $\dot{E}$ and the potential drop in the polar gap $\Delta\Psi$ hint that
emission properties are related to the particle acceleration process in a
pulsar's magnetosphere.
