Summary: This paper is concerned with the existence of global solutions to the Cauchy problem of a hyperbolic-parabolic coupled system with large initial data. To this end, we first construct its local solutions by the standard iteration technique, then we deduce the basic energy estimate by constructing a convex entropy-entropy flux pair to this system. Moreover, the \(L^\infty\)-estimates and \(H^2\)-estimates of solutions are obtained through some delicate estimates. In our results, we do not ask the far fields of the initial data to be equal and the initial data can be arbitrarily large which generalize the result obtained in the paper by M. Zhang and C. J. Zhu [Proc. Am. Math. Soc. 135, No. 4, 1017–1027 (2007; Zbl 1112.35005)].