Abstract: The discrete time-cost trade-offs problem(DTCTP,for short) is a most widely concerned with bi-criteria optimization model in project scheduling literatures,which has been studied under three possible objectives.(1)P1:the so-called deadline problem involves the scheduling of project activities in order to minimize the total cost of the project while meeting a given deadline.(2)P2:the budget problem aims at minimizing the project duration without exceeding a given budget.(3)P3: the time/cost profile problem involves the generation of the complete efficient time-cost profile over the set of feasible project durations.However,the literature on the DTCTP with time-switch constraints are sparsely paid attention.In this paper,we firstly introduce the problem description of time-switch constraints,and then build the arithmetic model of the DTCTPTSC_P2;From the point view of practicality,a genetic algorithm is developed to solve the model.Finally,a project example based on real-life situation is used to validate the model and the algorithm.At the same time,the results show that the model plays an instructional role for contractor to more closely control the project's scheduling.

Key words: project scheduling, time-switch constraints, discrete time-cost trade-offs, genetic algorithm