The invention discloses an ash handling system with coal gasification method and an ash handling method, and the ash handling system comprises a fly-ash filter, a fly-ash gathering tank, a fly-ash discharging tank and a fly-ash warehouse which are connected in sequence, wherein the fly-ash gathering tank is arranged in the bottom of the fly-ash filter, a synthesis gas outlet pipe is arranged on the top of the fly-ash filter, and the synthesis gas outlet pipe is connected to a wet-cleaning unit, the top of the fly-ash filter is also connected to a high pressure blowback air pipe. The ash handling system also comprises a decompressor and a gas buffer tank, wherein the bottom of the fly-ash discharging tank is directly connected to the fly-ash warehouse through the decompressor, the gas buffer tank is connected to the bottom of the fly-ash discharging tank and is used for introducing high pressure gas to the fly-ash discharging tank, and a first discharging control valve is arranged between the fly-ash gathering tank and the fly-ash discharging tank, and a second discharging control valve is arranged between the fly-ash discharging tank and the decompressor. The ash handling system with coal gasification method and the ash handling method solve the problems of high equipment investment and complex operation brought by diverse and complicated processes in prior ash handling process with dry method.