The invention relates to a ballast injection type in-situ measurement device for acoustic characteristics of bottom sediments. The device comprises an external supporting mechanism, an injection driving mechanism and a monitoring measuring mechanism, wherein the external supporting mechanism comprises a polygonal support frame fastened through bolts and a guide pipe; the injection driving mechanism comprises a hoisting head, a guide rod, a moveable pressing plate, a mounting flange, a ballast lead block and a probe rod; the monitoring measuring mechanism comprises a state monitoring sensor component, an acoustic sensor component and a monitoring measuring circuit component; and the measuring process is finished by respectively adopting the real-time monitoring mode and the self-contained mode by judging if the measurement device and the deck control platform are connected through a communication cable. Obviously, the external supporting mechanism is capable of ensuring the stability of the measurement device at the bottom-sitting moment at the seabed; the configurations of the guide pipe and the guide rod can cause the probe rod to drive an acoustic energy converter to more stably inject into the sediments; the in-situ measurement process for the acoustic characteristics can be automatically judged and controlled on the basis of the collection for the seabed state parameters of the measurement device; and the monitoring measuring mechanism has excellent expandability.