The invention discloses a construction waste crushing device with a dust collection function and a method. The crushing device comprises a supporting base plate, a supporting frame, a crushing box, astanding box and a dust collector. A crushing assembly is movably connected with the interior of the crushing box, a driving motor is arranged on the outer wall of the crushing box and connected withthe crushing assembly, a material guiding slope plate and oscillation mechanisms are arranged inside the crushing box separately, the material guiding slope plate is located below the crushing assembly, a material separating sieve plate is arranged between the oscillation mechanisms, and the material separating sieve plate is located below the material guiding slope plate; the crushing method comprises the following steps of 1 material mixing and crushing, 2 oscillating and separating, 3 standing and dust removal and 4 maintaining. The crushing device is simple in structure, high in crushing efficiency and good in crushing effect, collected building waste granules are uniform, and follow-up utilization is convenient; the crushing method is reasonable and orderly, easy to control, automaticand efficient, the labor intensity of workers is lowered, and the service life of the device is prolonged.