The invention relates to the technical field of shield tunneling machine construction, in particular to a dreg screening device and screening method for shield construction. The dreg screening devicecomprises an original screening device, a vibrating motor of the original screening device is connected with a control module and an ultrasonic liquid level sensor which is arranged on the inner sideof the box wall of a screening box and is used for detecting the stacking height of dregs, the control module of the dreg screening device is used for reading the information detected by the ultrasonic liquid level sensor constantly, moreover, a lifting motor is arranged at one end of a screen, one end of the screen is driven to ascend or descend through the motor, so that the screen is inclined.According to the system, the working state of the vibrating screen is judged in real time and online, so that the matching condition between the state of materials when being screened and current treatment capacity is judged, the working parameters of the vibrating screen are automatically adjusted, and the requirements for the treatment capability and the treatment efficiency when the feeding amount and the property of the dregs are changed are met.