The invention discloses an air purifying device.The air purifying device comprises a preliminary filtering mechanism, a draught fan and a secondary filtering mechanism, the preliminary filtering mechanism is provided with a filter screen, and the secondary filtering mechanism comprises a concave cavity portion located at the front side and a purifier portion located at the rear side; the left side and the right side of the concave cavity portion are each provided with a mounting groove, the upper portion of each mounting groove is provided with a first clamping hook, the left side and the right side of the preliminary filtering mechanism are provided with insertion pieces which are in one-to-one correspondence with the mounting grooves, the upper portion of each insertion piece is provided with a second clamping hook, the lower portion of each insertion piece is provided with an elastic piece, each first clamping hook and the corresponding second clamping hook are buckled together through an elastic extending-and-contracting buckle of the corresponding elastic piece, and the preliminary filtering mechanism and the secondary filtering mechanism are fixed.The device is high in air purification efficiency, the preliminary filtering mechanism can be connected with and detached out of the secondary filtering mechanism conveniently, and it is convenient to clean and maintain the device.