The invention relates to the technical field of leg support and discloses a ceramic tile laying leg supporting device preventing knees being injured, comprising two fixing rods, two first struts, a knee protection device, two hollow pipes, two adjusting bolts, two cross bars, two arc-shaped rods, two supporting rods, four through holes, a hip supporting device, two fine adjustment supporting devices, two first fixing ropes and two second fixing ropes; the two first struts are fixed at the tops of the relative faces of the two fixing rods; the knee protection device is actively connected between the two first struts; and the bottoms of the two fixing rods are actively inserted into the two hollow pipes. In this invention, the hip of a worker can sit at the top of the hip supporting device directly; the device is easy and saves labor; the worker is convenient to lay ceramic tile; the working efficiency of laying ceramic tile is improved; the collision force contacting with the ground canbe buffered effectively, so the supporting device can achieve protection effect on knees.