The invention provides a 3D printed concrete constructability test device and method. The device consists of a bracket, a load container, a moulding die and a laser displacement detector. The upper part of the bracket is a support sleeve, the bottom is a base plate, and the support sleeve is fixedly connected to the base plate through support rods. The load container has an opening upper part anda sealed bottom, and passes through the support sleeve. The moulding die is used for making a to-be-tested mortar model. The laser displacement detector includes two laser displacement sensors and a display screen, a longitudinal laser sensor is fixedly installed on a side wall of the load container, a horizontal laser sensor is disposed on the base plate through a movable fixation apparatus, andthe display screen is connected to the two laser displacement sensors through a wire. The device and method provided by the invention can completely simulate the printing situation in the actual process, and achieve ultra-high reduction of deformation in the printing process, and can make a vertical deformation curve in the loading procedure visible directly, and by simulating the printing time interval of different layers, can study the influence of interlayer printing time interval on constructability, and provide reference for determining the vertical printing rate.