Building acoustic simulation tools have often been used to ensure a room's acoustic performance, but they are rarely used in the early design stage. In this study, an acoustic simulation plug-in of Grasshopper for Rhino, Pachyderm, was combined with parametric design and a multi-objective optimization process to study the acoustic performance of a shoe-box-shaped concert hall in the early design stage. Three different factors of the sound field, sound pressure level A-weighting (SPL(A)), reverberation time (RT), and clarity 80 (C80), were discussed. One of the most famous shoe-box-shaped concert halls, Großer Musikvereinssaal, was selected as the comparison model. Two thousand results were generated through a multi-objective process in 36 hours. Compared with Großer Musikvereinssaal, the Pareto front of the 2000 results showed better performance in various factors of the sound field according to what it optimized.