The soliton excitation of a onedimensional Heisenberg antiferromagnetic chain with bond alternation was studied. In the Hamiltonian of this antiferromagnetic model

the interactions between the nearest neighbor lattice and next nearest neighbor lattice，Dzyaloshinskii-Moriya interaction and constant external magnetic field were considered. By using Holstain-Primakoff transformation and the multiscale method

spin wave frequency ω was obtained when nonlinear term in the system was neglect

and two bright soliton solutions of the two sets of sublattice were obtained when nonlinear term was considered. Finally

the effects of the wave vector k and bond alternation strength m ( the nearest exchange interaction parameter ratios J′

1

/J

1

)on ω，the soliton peak value，width and energy were discussed. The results show that ω can be divided into optical branch ω

+

and acoustic branch ω

－

. ω does not exist near kb=0

±2π（b is the distance between the two nearest neighbor cells). Acoustic branch ω

－

corresponds to bright soliton solution

optical does not. When J

1

is certain

the smaller the m is

the smaller the gap between ω

+

and ω

－

will be. The peak width，phase velocity，group velocity and energy quantum of the two bright soliton solutions are of the same values，but the envelop amplitude and phase are different with the same parameter. The energy quantum of the soliton solutions is smaller than the energy quantum of the spin wave solution when nonlinear term is not considered

so the two soliton solution is stable. The m affects not only the relative peak value

but also the relative phase of the two solitons.The peak value of two soliton solutions vary with the changes of m and k

but the change is not the same. The peak width does not increase monotonously with the crease of k

nor does it increase monotonously with that of m.