Parameters of intraframework potential function suitable for aluminophosphate-5($AlPO_4$-5) are obtained by the constraint method. Using these parameters, we calculated the stabilization energy and the second derivatives of the stabilization energy of framework atoms and they are compared with those of zeolite A. It is found that oxygen atoms of $AlPO_4$-5 framework are more stable than those of zeolite A. And aluminum atom is also more stable than that of zeolite A. On the other hand, the phosphorus atom of $AlPO_4$-5 framework, in which the silicon atoms of aluminosilicate are replaced by phosphorus atom, is less stable than the silicon atom of aluminosilicate framework of dehydrated zeolite A.