The invention discloses a calibration method of a direct reading type dust concentration detector. The calibration method comprises the following steps: (1) assembling the calibration device of the direct reading type dust concentration detector; (2) obtaining values through a standard sampling device; (3) obtaining values through the direct reading type dust concentration detector; (4) recoveringdust, and purifying; and (5) comparing and calibrating: comparing a dust concentration value obtained by the direct reading type dust concentration detector with a dust concentration value obtained by the standard sampling device, calculating an error, then adjusting the K value of the direct reading type dust concentration detector, and amending the error, so that the calibration of the direct reading type dust concentration detector is completed. Through the adoption of the above manner of the calibration method disclosed by the invention, the dust concentration value obtained on the basisof the self-designed calibration device is used as a fiducial value, and is compared with the dust concentration value which is directly obtained by the direct reading type dust concentration detector, and then the direct reading type dust concentration detector is rectified; and the obtained fiducial value is high in accuracy and high in stability, so that the situation that the calibration accuracy of the direct reading type dust concentration detector is high can be guaranteed.