Abstract: In this paper,the Cauchy problem of the classical Keller-Segel chemotaxis model with initial data of large mass is considered.By the Green’s function method and scaling technique,we prove that if‖u₀‖■‖u₀‖■ and κ‖Δv₀‖Lp are less than some constant,then the problem always admits a unique global classical solution,even when the initial mass‖u₀‖L¹ is large.Moreover,the decay rates of the classical solution are also obtained. 

Key words: Chemotaxis, Keller-Segel, Large mass, Global existence, Decay rate