Solar radiation which reaches the earth surface in Palmyra city has high rates, so we introduce this research to study the operation of a solar electric power plant with parabolic trough solar collector type. Electric power plants are usually designed to operate at nominal design power and flow rate, pressure, specific steam temperature. In this case the obtained efficiency is relatively high, but the real conditions in which the plant operates and supplies the electric grid, in addition to the climate variations during monthes and seasons, all lead to a deviation in power value from nominal value, so the plant operate at partial loads. We used the analytical method in this research to study the variation in power plant parameters as the steam turbine load changes. In other words, the study of main plant parameters variation due to variable partial loads. We calculated steam pressure variations through turbine stages and its effect on changing steam flow rate to the recovery water heaters. In addition, we calculated the amount of heat consumed through turbine unit, turbine unit efficiency, and the total efficiency of the power plant.