In this paper, a low-loss and wavelength-insensitive asymmetric 1×5 arbitrary optical power splitter is designed and optimized, which is composed of a three-branch and two Y-branch elements. A low-loss and wavelength-independent arbitrary 1×5 optical power splitter can be obtained. Asymmetric 1×5 optical power splitters of different output ratios are fabricated using silica-based planar lightwave circuit (PLC) technology on a 6-inch quartz substrate. The measured results show that the ILoutput1, ILoutput2∼5, UNIFoutput2∼5, PDL, and WDL of the output ratio 33%:67%, 50%:50%, and 95%:5% are less than (5.302 dB, 8.483 dB, 0.422 dB, 0.191 dB, 0.345 dB), (3.46 dB, 9.71 dB, 0.28 dB, 0.119 dB, 0.231 dB), and (1.52 dB, 14.15 dB, 0.44 dB, 0.366 dB, 0.561 dB), respectively, in the wavelength of 1.27 μm, 1.31 μm, 1.49 μm, 1.55 μm, and 1.625 μm.