According to urban train running status, this paper adjusts constraints, air spring and lateral damper components running status and vibration signals of vertical acceleration of the vehicle body, combined with characteristics of urban train operation, we build an optimized train operation adjustment model and put forward corresponding estimation method-- wavelet packet energy moment, for the train state. First, we analyze characteristics of the body vertical vibration, conduct wavelet packet decomposition of signals according to different conditions and different speeds, and reconstruct the band signal which with larger energy; we introduce the hybrid ideas of particle swarm algorithm, establish fault diagnosis model and use improved particle swarm algorithm to solve this model; the algorithm also gives specific steps for solution; then calculate features of each band wavelet packet energy moment. Changes of wavelet packet energy moment with different frequency bands reflect changes of the train operation state; finally, wavelet packet energy moments with different frequency band are composed as feature vector to support vector machines for fault identification