The invention discloses a testing device and measuring method for measuring early-age anti-cracking performance of concrete with different thicknesses.. The testing device comprises an anti-cracking device, working strain gauges, a temperature compensation gauge, a strain acquisition system and a computer, wherein the working strain gauges and the temperature compensation gauge are installed on the anti-cracking device, a signal input terminal of the strain acquisition system is connected with the working strain gauges and the temperature compensation gauge, and a signal output terminal of the strain acquisition system is connected with the computer. The testing device is characterized in that the anti-cracking device is in the shape of a cone frustum and comprises a bottom plate, an inner steel ring and an outer template, wherein both the inner steel ring and the outer template are installed on the bottom plate, the outer template is the shape of a cone frustum, and the inner side of the inner steel ring is provided with at least five layers of working strain gauges in the height direction. The testing device provided by the invention is simple in structure, convenient to disassemble, and applicable to the measurement of the early-age anti-cracking performance of concrete with different thicknesses in one anti-cracking device.