Turbulence structures in transition region were characterized in a circulating fluidized bed (CFB) with square cross section. The investigations were carried out using a Particle Dynamic Analyzer (PDA). Both the axial and lateral velocity profiles of the solid phase were obtained. The axial profiles show the core-annulus structure in this region. Temporal evolutions of the particle velocity fluctuation indicate their great agitation and non-homogeneity with time and space coordinate. The studies on turbulent density and turbulent energy illustrate that the turbulence in the CFB is an anisotropic turbulence, and the particle turbulent density decreased sharply as the measurement points move away from the wall. To further understand the microstructure of the particle velocity fluctuation, wavelet analysis was also adopted. The vivid imagines show that it is an anisotropic turbulence at all scales and its fractal and dissipative structure.