According to the process of the mutual reaction of the population number at each energy level of the un-equilibrium mixed gases flowing in flow laser and the intensive emission reaching the stable oscillation, and the numerical simulated calculation results of the corresponding 3-dimensional distribution states, the simplified calculation formulae of the basic properties of the corresponding oscillator and amplifier are developed. The calculation results of these formulae are agree well with the experimental measures of many kind devices with various cavities. Concretely comparing and analyzing the basic properties of flow laser oscillator and amplifiers, some basic principles are gained for providing the theory basis of the optimum design of the corresponding devices.