The present disclosure provides an in-mold injection molding process for a Printed Circuit Board Assembly (PCBA) soft material, including the following steps: 1) preheating a Polyethylene Terephthalate (PET) thin film; 2) printing patterns; 3) preparing a diaphragm A; 4) laminating a diaphragm on a Flexible Printed Circuit (FPC) board; 5) scraping printing ink; 6) scraping an adhesive; 7) preparing an inner diaphragm B; and 8) placing prepared diaphragm A and FPC board laminated diaphragm in a mold cavity of an injection mold of a Haitian 130T injection molding machine, preheating injection mold to 30° C., and injecting Thermoplastic Polyurethane (TPU) resin through an injection hole, so that diaphragm A is on an outer side of a product mobile phone protective shell, FPC board laminated diaphragm is on an inner side of the product mobile phone protective shell, and temperature of the TPU resin is at 180° C.