Optical input/output chip and distributed computing system, including: output sub-chip includes first light processing module to form N first light branches output from laser source, divide and modulate each first light branch into M first light sub-branches according to M wavelengths, form second optical branches containing N different modes from N modulated first optical branches before being output in first polarization state; input sub-chip includes second optical processing module, to form N third optical branches containing same mode from N second optical branches containing different modes, divide out part of light in each third optical branch having been converted from first polarization state to second, and form first polarization state again, combine and demodulate light in first polarization state without conversion in original third optical branch after having been divided into M second optical sub-branches according to M wavelengths respectively. Thus increasing both communication rate and bandwidth effectively.