Experimental study on unconfined volume dispersion and single ignition of few dosage of mixed ternary fuel is successfully done, based on dispersed detonation. Experimental results show that single ignition process of mixed fuel containing aluminum powder, propylene oxide and TNT can be divided into four stages, overpressure within its explosion field firstly increases, then decays with increase of distance, and distribution of overpressure field is similar. Overpressure of binary mixed fuel containing aluminum powder and TNT decays like TNT charge with increase of distance, but its value is higher than TNT charge′s in the same mass at further distance. The continual action time of plus pressure during cloud detonation of mixed ternary fuel containing aluminum powder,propylene oxide and TNT reaches magnitude of 10 ms and is about 100 times than TNT charge′s.