Reasonable facility location has great strategic significance to catch market share when an enterprise enters a new market. Competitive facility location considers the problem of how to launch new facilities in a market, where competitors run their existing facilities. A capacitated facility location model is proposed to minimize the cost of the new enterprise under the condition of achieving specific market share. A two-way selection mechanism is designed to determine the service relationship between facilities and consumers, and a simulated annealing framework combining the two-way selection mechanism is presented to solve the model. The relationship between enterprise's market share, cost and the expected market share indicator is analyzed using numerical example, and the validity of the three strategies of defensive location of the original enterprise is compared.