The invention belongs to the firefighting field, and particularly relates to a dry powder injection system and a fire fighting truck. The dry powder injection system comprises a dry powder fluidization tank, a high-pressure gas source, a dry powder injection device and a blowing-assisting device, wherein the high-pressure gas source can communicate with the dry powder fluidization tank in a pressure-adjustable mode; the dry powder injection device communicates with the dry powder fluidization tank for injecting dry powder gas flow subjected to fluidization treatment; and the blowing-assistingdevice can guide blowing-assisting gas flow with set pressure to the dry powder injection device, so that set injection pressure which meets the requirements of the dry powder injection device is met.Based on the technical scheme, the embodiment of the invention at least can solve the problem that blowing-feeding pressure of jacking a dry powder fire extinguishing system of the fire fighting truck is insufficient.