A time-cost optimization modeling method of a building project structurized as step unit activities applying various techniques and resources is provided. To display a time index and a cost index to be optimized as technique and resource functions, the method includes a step of defining a determination flat surface as the minimum extreme point and the maximum extreme point of the cost index and the time index obtained when the construction project progresses by applying the techniques and the resources, a step of mapping the determination flat surface with a standardization index flat surface and calculating one or more optimized values through genetic algorithm based on chromosomes having the techniques and the resources for each unit activity as genes in regard to standardized index points in the standardization index flat surface, and a step of generating one or more construction projects by combining the techniques and the resources corresponding to the value. [Reference numerals] (AA) Start; (BB) End; (S41) Structure a project by step unit activities to which more than one alternative can be applied; (S42) Define a determination space by minimum extreme points of indexes within a basic index space; (S43) Map the determination space onto a standardized index space which is dimensionless and normalized; (S44) Calculate at least one optimized value through a genetic algorithm based on chromosomes having alternatives to each unit activity as genes in regard to standardized index points; (S45) Generate at least one project by combining alternatives corresponding to at least one optimized value