Poly(methyl methacrylate) (PMMA) have been widely used for many applications due to the excellent transmittance like glass as well as good mechanical properties and easy processing. However, PMMA can be easily scratched, so various resistant coating materials are often necessary. To overcome the disadvantage, self-healable cross linker for PMMA was investigated. This cross linker was synthesized from 1,6-Hexanediol diglycidyl ether and acrylic acid. It can undergo ester exchange reaction during thermal treatment. In this paper, the effect of cross linker concentration on the self-healing efficiency of the PMMA network was studied experimentally. To characterize the self-healing properties of PMMA network, stress relaxation test was performed with dynamic mechanical analyzer (DMA). Thermal properties are also studied with DSC and TGA. It was found that the dynamic covalent bond allow the melt processing and damage recovery of the cross linked PMMA.