Effects of heat loss on the flame propagation in the Self-propagating High-temperature Synthesis (SHS) are examined with a heterogeneous theory based on the premixed mode of the bulk flame propagation supported by the non-premixed reaction of dispersed nan-metal particles in the liquid metal. This formulation allows for volumetric heat loss throughout the bulk flame, finite rate Arrhenius reaction at the particle surface and temperature-sensitive Arrhenius mass diffusion in the liquid. The results show that the burning velocity decreases with increasing heat loss, that at a critical heat-loss rate the flame extinguishes as indicated by the turning-point behavior, and that the extinction is sensitively affected by the mixture ratio, the degree of dilution, the initial temperature of the compact, the size of the non-metal particles and the size of the compact. It is further shown that the theoretical results agree well with available experimental data, indicating that the present formulation captures the essential feature of the non-adiabatic heterogeneous SHS process.