In this paper, we present a diode-pump continuous wave laser amplifier chain where master the oscillator power amplifier (MOPA) architecture is used. The laser amplifier chain consists of two Yb:YAG surface-doped slab laser modules and the 1030nm fiber laser is used as seed. We theoretically calculate the conditions for obtaining high output laser power and systematically analyze the advantages of surface-doped slab. The maximum output power is 6.1 kW and the optical to optical conversion efficiency is 27% when the pump power is 22 kW at room temperature. The beam quality (β) is 2.8 times diffraction limit. These results demonstrate that the surface-doped slab structure has the potential to obtain high output laser power.