Abstract: Effective competition in an industry is a combination of competitive vitality and scale economy, this paper analyzed the competition vigor from three aspects: the market concentration, enterprises behavior and market performance, found that although the market concentration is decreased, but power industry still maintained a high profit rate, but the power generation industry still exists a high degree of monopoly, so the market is lack of vitality. Then, we used DEA model analyzed the data of 31 quoted eclectic companies, found that due to the expansion of production capacity, large power generation group showed a trend of decreasing returns to scale. At the same time, despite the efficiency is very low, many small local power enterprises are still in operation. Therefore, the majority of power generation enterprises are diseconomies of scale.