Response surface methodology was used to optimized soaking and roasting conditions and monitor organoleptic properties of roasted Platycodon grandiflorum tea. In soaking and roasting processes based on the central composite design with variations in threonine/sucrose concentration for soaking of Platycodon grandiflorum, roasting temperature and roasting time, coefficients of determination ($R^2$) of the models were above 0.86(p<0.05) in organoleptic properties. The maximum conditions predicted for each corresponding organoleptic properties of roasted Platycodon grandiflorum tea were 1.64% threonine concentration, 137.83$^{circ}C$ and 27.76 min in aroma, 1.46% threonine concentration, 136.1$0^{circ}C$ and 25.19 min in taste, and 1.39% threonine concentration, 136.44$^{circ}C$ and 29.05 min in overall flavour. The optimum condition ranges for organoleptic properties of roasted Platycodon grandiflorum tea were soaking in 1.40~1.64% threonine concentration, and roasting at 136.10~137.9$0^{circ}C$ for 25.19~29.00 min.