We propose and fabricate a multi-primary-color (MPC) quantum-dot down-converting film (QDDCF). A four-primary-color QDDCF composed of red (R), yellowish green (YG), bluish green (BG), and blue (B) subpixels was fabricated via totally five rounds of photolithographic processes. A verification platform was built up using a laser projector, and the measured results show that the QD film can expand display color gamut to 118.60% of Rec. 2020 and can cover the entire Pointer's gamut. The issues of blue light absorption and film thickness are analyzed in detail. The combination of MPC technology and QDDCF is a potential strategy to realize ultra wide color gamut for emerging display technologies.