This researche designed and constructfabricatedion of a 90° kind of based on InP - 4 x4-90 ° of MMI opticalmixer hybrid based on an InP 4×4 MMI, systematically introducinges the InP base 4×4 - mixer chip structure and operatingworking principle of the chipMMI light., The optical hybrid was fabricated with the light of mixer chip InGaAsP waveguide layer material, InP cladding layer and InP InP substrate material., Tthe width of the single mode waveguide was designset to be 2.6 μm, and multimode interference waveguide ( MMI) the length and width of multimode interference waveguide (MMI) the design forwere set to be 844 μm and, 20 μm , respectively. Using theThis work used three dimensional beam propagation method (3Dd- BPM) to , I analyzed the error tolerance of the refractive index, core layer thickness, the width and the waveguide length of waveguide error tolerance,. It was found that in the 1535nm ~ 1565 nm wavelength range , optical hybrid’sthe light of the design of mixer chip insertion loss is less than 1 db and phase deviation is less than 5° in the wavelength range of 1535 ~ 1565 nm, phase deviation is less than 5 °. The optical hybrid was design of light mixer chip fabricatedmade in laboratory, and tested on the coupling test platform to test,. The test results shows that phase deviation is less than 5° in the wavelength range of 1535 ~ 1565 nm, which is consistent with the simulation resultin 1535 ~ 1565 nm wavelength range, the light of the phase deviation is less than 5 ° mixer chip.