A non-isothermal molding filling process for a non-Newtonian viscoelastic fluid is investigated in this work. An extended smoothed particle hydrodynamics with diffusive term and kernel gradient correction (extended SPH_DTKGC) method is first presented to simulate the non-isothermal molding filling for the viscoelastic fluid based on the coupled eXtended Porn-Porn (XPP) and thermal power-law model. Meanwhile, a suitable discrete temperature scheme in the SPH frame is proposed. And a new way to treat the zig-zag boundary is given and expected to deal with arbitrary shaped rigid wall. Subsequently, the merits of the proposed boundary treatment are demonstrated by a spin-down problem and the filling process in a C-shaped mould. The ability of the extended SPH_DTKGC to simulate the viscoelastic free surface flow is verified by the several classical problems. Two benchmark problems are presented to display the reliability of the proposed temperature scheme. The non-isothermal filling process for a power-law fluid is performed to show the feasibility of the extended SPH_DTKGC to simulate the non-isothermal mold filling process. Then the extended SPH_DTKGC method combined with other improvements is applied to the non-isothermal filling processes based on the coupled XPP and power-law model. Especially, the influences of the parameters of the XPP model on the physical quantities, such as the first normal stress difference and the temperature field, are numerically predicted. (C) 2015 Elsevier Ltd. All rights reserved.