We study theoretically the Gaussian laser pump field and dump field conditions for producing ultracold cesium molecules from ultracold atomic condensates by the two-color photoassociation through the stimulated Raman adiabatic passage (STIRAP) in a tunneling four-level structure.An excited molecule |bk〉 is produced in an outer excited state from the ultracold atoms at the initial state |a〉 via the pump field.Then,the excited molecule |bk〉 is converted to the inner excited molecule |bv0〉by the tunneling coupling.Furthermore,the dump field drives |bv0〉 to the ground molecular state |g〉.In this progress,the detuning of pump field Δp is fixed at -(0.16 cm-1)32,and the detuning of dump field Δd is satisfied with the two-photon resonance condition,which can be obtained from the dark state solutions of the coupled mean-field equations.In the two-color photo association,we can control the two effective Rabi frequencies (Ω0p,Ω0d),the delay coefficient (α) and the width (T) of the two laser fields and obtain the high conversion efficiency (η≥0.9) as the optimum conditions of the pump and dump fields.In the meantime,the population dynamics of atoms and stable bound ground molecules with the conversion efficiency at 0.919 are investigated at specific parameters,where Ω0p=600×105 s-1、Ω0d=160×105 s-1、α=1.9、T=0.9×10-4 s.The unequal effective Rabi frequencies (Ω0p ≠Ω0d) are to the benefit of the coherent transfer from the atoms to the ground molecules through the STIRAP for the wide ranges of the delay coefficient and the width.Furthermore,we also investigate comparatively the cases of the small and large equal effective Rabi frequencies (Ω0p=Ω0d) for maintaining the delay coefficient and the width.The results have demonstrated that the conversion efficiencies are decreased sharply.Therefore,only the matched the effective Rabi frequencies,the delay coefficient and the width of the two laser fields can convert efficiently the ultracold atoms to the stable ground ultracold molecules.