Ion beam assisted crystallization behavior of sol-gel derived $PbTiO_3$ thin films, deposited on bare silicon(100) substrates by spin-casting method, has been investigated. Ar ion bombardment was directly conducted on the spincoated film surface with or without heating the film from room temperature to $300^{circ}C$. Ion dose was changed from $5{ imes}10^{15}$ to $7.5{ imes}10^{16}$ $Ar^-/cm^2$. Formation of (110) oriented perovskite phase was obseerved with ion dose above $5{ imes}10^{16}; Ar^+/cm^2$. Crystallization of $PbTiO_3$ thin film could be enhanced with increasing the Air ion dose, or heating the substrate during ion bombardment. Crystallization of the $PbTiO_3$ films by ion bombardment was related to the local heating effect during ion bombardment.