To explore the hot-spot forming mechanism of heterogeneous solid explosives under the complicated impact environment, in the "hot-spot" model of one-dimensional viscoplastic holes collapse, different patterns of external forces, such as tension and compression were considered and the effects of temperature and damage on the mechanical performance of explosive were introduced. The "hot-spot" forming model of holes collapse for explosive was established. The movement regularity of holes under the complicated impact environment was simulated. The formation model of hot-spots of PBX9404 under two kinds of different external forces including continuous compression, and tension and compression alternate was compared and analyzed. Results show that under continuous compression action of greater than 400 MPa, the holes can produce hot spots, whereas under the alternating action of tension and compression of 250 MPa, the holes can produce hot spots. So the alternating action of tension and compression is easer to produce the hot spots.