An optical film, a backlight module and a manufacturing method of the optical film are provided. The optical film is composed of a quantum dot gel layer. The quantum dot gel layer includes a first polymer and a plurality of quantum dots dispersed in the first polymer. The first polymer includes 1 to 5 wt % of photoinitiator, 3 to 20 wt % of scattering particles, 20 to 40 wt % of thiol compound, 5 to 30 wt % of monofunctional acrylic monomer, 20 to 40 wt % of multifunctional acrylic monomer, 1 to 5 wt % of organosilicon grafted oligomer, and 500 to 1500 ppm of inhibitor.