A positioning system includes a first working platform, a second working platform spaced apart from the first working platform, and a carrier. The carrier is fixed on the first working platform or the second working platform. The carrier has at least one fixing member for fixing the substrate onto the carrier and fixing the mask onto the substrate. The substrate has at least one fixing hole formed thereon for receiving the fixing member, and the mask has at least one positioning hole formed thereon in alignment with the fixing hole. The fixing member is capable of inserting sequentially through the fixing hole of the substrate and the positioning hole of the mask.