The output power of a 6328Å He-Ne laser is calculated from the solution of rate equations in the sixteen-level system. The processes leading to population and decay of neon levels in dc discharged plasma are introduced in this system with many kinds of transition probabilities. These probabilities are shown explicitly as a function of operating parameters such as the discharge current, gas pressure and inside radius of a laser tube. From the results the quantitative values of the output power are calculated as a function of operating parameters. The calculated results agree with the experimental results which are measured with three laser tubes having different structures and gas pressures.