Laser phenomena in random media have been studied bas ed on the localized theory for optical waves in finite random media. The relatio n ship between spatial localization and amplification for quasi_state modes ha s been investigated by use of the finite difference time domain method. T he spatial profile and the spectra characteristics of quasi_state modes are dete r mined by analyzing the localized processes of optical light beams in random medi a without gain. The amplification and threshold of quasi_state modes are analyze d in random media with gain. Results show that the quasi_state mode with a stron ger spatial localization has lower threshold and can be amplified preferentially .