The Archean continental crust is mainly composed of tonalite-trondhjemite-granodiorite (TTG) rocks. Experimental studies have established that these TTG rocks can be generated by partial melting of basaltic rocks. The pressure of partial melting can be linked with tectonic setting. The mostly used approach to constraining the pressure of partial melting is thermodynamic modelling. However, source compositions and partition coefficients used for the modelling are different in different studies, which result in different pressure constraints and tectonic setting interpretations. In this study, a melt Gd/Dy ratio-based barometer for TTG petrogenesis was established. La/Yb and Gd/Yb were not used because Gd/Dy based barometer is less affected by the uncertainty about the enrichment of the source and the temperature of partial melting. We first developed a model source composition for TTG petrogenesis by analysing experimental data about partial melting of basaltic rocks and differentiation trends about basaltic rocks. Then, thermodynamic modelling was used to obtain the phase proportion of this source composition at various pressure, temperature, and water content conditions. Finally, batch partial melting model was used to calculate the Gd/Dy of melt at various conditions. Temperature dependent partition coefficients were used in the calculation. Using the newly established geobarometer, the petrogenesis pressures of most TTG rocks were constrained to be 1.1 GPa - 1.3 GPa. Therefore, subduction is not needed for the formation of TTG rocks.