To understand the solidification process of 2, 4-dinitroanisole(DNAN), the temperature field in the central axis in the solidification process was tested by Bragg gratings. The microscopic phenomenon of natural convection of liquid phase was considered. The temperature field, flow field and phase interface position for the solidification process of DNAN were calculated by volume-control method. The formation of shrinkage holes and shrinkage porosities were predicted by considering both critical solid phase fraction and feeding length. Results show that the temperature hysteresis appears at about 96 ℃ and most obvious in the center. The maximum velocity of natural convection of the early stage of liquid reaches 10^-3 magnitude(m·s^-1). This natural convection helps to transfer mass and to accelerate the process of solidification. Under no feeding conditions, the phase interface in the solidification process of DNAN is V-shaped, it shrinks and transfers from bottom to top. After contraction and solidification, the shrinkage holes distribute continuously in the central axis of explosive, and the maximum porosity in the center is 0.38.