In a commercial parabolic trough solar power plant (PTSPP), the solar field (SF) is large-scaled and consists of hundreds of parabolic trough collector (PTC) loops. The PTSPP performance is determined by an appropriate operation strategy of the SF, which is implemented by adjusting the outlet temperature, the flowrate, and the flow distribution through the valves and pump to make the PTSPP output cost-effective. Majority of the published literature study the behavior of the SF with an assumption that all the PTC loops have uniform perfect performance. Due to the lack of appropriate model and algorithm, although operating with nonuniform and degraded PTCs is inevitable for a realistic SF, there is scarcely any literature studies how to develop an optimal operation strategy under this situation. The present paper aims at solving this problem by establishing a PTSPP model and developing an improved operation strategy (I05). The PTSPP model consists of an improved thermal hydraulic model of the SF and a simplified but effective model of the power block, and the IOS combines the features of both global and distributed operation strategy. Based on the model and the 105, the mechanism of optimization is illustrated in a uniform case, and then according to the comparison and analysis, the most appropriate strategy for the nonuniform case is determined among three representative strategies. Compared with the traditional operation strategy, the chosen strategy can improve the net electric generation by 3.4% with the low computational cost and good engineering feasibility.