This paper presents the design of a new Fresnel lens for GaInP/GaInAs/Ge multi-junction solar cells, with which uniformity irradiance distribution can be realized within the broadband solar spectrum from 300 nm to 1800 nm. By actual tests, the quantum efficiency spectrum of GaInP/GaInAs/Ge multi-junction solar cells and refractive index dispersion curve of silicone, the body material of the lens are obtained. On this basis, the new Fresnel lens is optimized by combining the multi-wavelength and multi-focus method. Based on this optimization method, the lens model is set up with geometrical concentrator ratio 625× and ring width 0.3 mm, and calculation models for concentrating performance parameters including optical efficiency and uniformity are established. The concentrating performance of the new Fresnel lens is analyzed by Monte-Carlo ray-tracing simulation approach and experimental testing. Results indicate that in the broadband solar spectrum from 300 nm to 1800 nm and within the spectral response band of three subcells, uniformity is well achieved with high optical efficiency. The uniformity is higher than 75%, and the optical efficiency is more than 80%.