Dye lasers are commonly used in the optical investigation because their solutions in organic solvents deliver tunable, coherent emission. They exhibit intense fluorescent, owning to some specific spectroscopic characteristics. One drawback of the laser dyes is that it shows excessive Triplet-State Losses (TSLs) the lack of theoretical predictions of fluorescence rates, Inter System Crossing (ISC), and phosphorescence in laser dyes prompted us to report on the predicted rates of radiative and non-radiative transitions of some laser dyes. Structural engineering by some substituents that influence the simulated rates of coumarin laser dye derivatives for an efficient operation was investigated. The NH2 functional group renders the coumarin 120 more fluorescents with reduced TLS than the other investigated materials.