For improving the collection efficiency of heliostat fields for solar tower power plants, the design and optimization of heliostat field layouts are needed. Based on the nonimaging optical design theory, a new method in which the field boundary is constrained by geometrical aperture of receiver and the efficiency factor of heliostat is proposed. The heliostat can be placed with higher efficiency by this method. The heliostat field layout is regular, which is helpful for the optimization of the configuration. Therefore, the response speed of the design and optimization of the field is improved. By using the Monte Carlo ray tracing method, the mathematical model of the concentration of heliostat field is created. The field configuration is optimized with parameter search algorithm. A new code for the design and optimization of the heliostat field layout is developed under the Matlab environment and validated by using the current PS10 field in Spain. A new heliostat field of 10 MW solar tower power plant which is located in Beijing is designed by using the new code. The mean annual optical efficiency of the designed heliostat field is 64.15% and is closed to that of PS10 field, which comes up to an international advanced level.