The invention discloses a multi-stage combined tunnel dust removal 
system and a dust removal method thereof. The dust removal 
system comprises a first-stage dust removal device, a second-stage dust removal device, a third-stage dust removal device, a 
sedimentation filter tank and a 
water storage device, the first-stage dust removal device comprises a first-stage dust removal outer 
barrel, an air inlet 
barrel and a rotary dust removal mechanism; an air inlet grid is arranged at an inlet of the air inlet 
barrel; the rotary dust removal mechanism comprises a first-stage dust removal inner barrel,a 
turbofan, a water mist spraying mechanism and a rotary 
power transmission mechanism; the second-stage dust removal device comprises a second-stage dust removal cylinder, a U-shaped 
pipe and a tubenest type condenser; the three-stage dust removal device comprises a three-stage dust removal cylinder, a 
corona electrode, a filter bag type dust remover and a rectification power supply, the filterbag type dust remover comprises a dust removal framework and a dust removal filter bag, a blowback 
pipe is arranged in the three-stage dust removal cylinder, and a plurality of pulse blowback valves are arranged on the blowback 
pipe. The dust removal 
system is novel and reasonable in design, convenient to implement, capable of efficiently removing dust generated in 
tunnel construction and reducingharm to human beings, high in practicability, good in using effect and convenient to popularize and use.