To investigate the influence of rice line, salt concentration and salt exposure time on proline accumulation, 23 indica rice lines were cultured on Murashige and Skoog (MS) medium supplemented with 0, 171, 342, 513 and 684 mM NaCl for 10 days. All three factors, especially rice line, significantly affected the proline accumulation. Among the salt-tolerant rice lines, Leuang Tang Mo showed the highest proline content. This line was then cultured under high salt concentration to determine the correlation between proline accumulation and chlorophyll index (CI). The addition of NaCl and exposure time significantly influenced both the proline accumulation and the CI. The proline content positively correlated with the CI. Consequently, the CI measurement was performed as a rapid method to select the salt-tolerance of Thai aromatic rice. To select for salt-tolerance by this developed method, 230 Thai aromatic rice lines were cultured on MS medium containing 513 mM NaCl for 8 days. The Hawm Naipon line manifested the highest CI and survival percentage, followed by Hawm Durian and Hawm Pae-palo, respectively. The survival percentage also significantly correlated with the CI.