A manufacturing method of a multi-wavelength laser array chip includes the steps of firstly, sequentially growing a buffer layer, a lower separate confinement layer and a multiple quantum well layer on a substrate; secondly, corroding part of the multiple quantum well layer, and using the corroded part as a passive optical combiner area and the rest part as an active area; thirdly, manufacturing medium mask pairs on the remained multiple quantum well layer; fourthly epitaxially growing an upper separate confinement layer on the upper surface of each of the passive optical combiner area and the active area; fifthly, removing the exposed medium mask pairs, and manufacturing gratings on the upper separate confinement layer on the active area; sixthly, extending a wrapping layer and a contact layer on each upper separate confinement layer; seventhly, etching an active waveguide on the contact layer of the active area, and etching a passive optical combiner waveguide on the contact layer of the passive optical combiner area; eighthly, manufacturing P electrodes on the active waveguide; ninthly, thinning the substrate, and manufacturing N electrodes at the back of the thinned substrate.