Because of the major structural component of PT. Victoria Beauty Industrial Purbalingga's new factory 1 and new factory 2 projects are typical steel frames; heavy machinery is required to move or lift steel during the construction of the frames. Lack of time planning in executing the steel frame erection work increases the possibility that the work will not be completed by the ideal time. This research examined the time and cost optimization of heavy equipment for erection work using the time-cost trade-off approach by increasing the number of cranes and extending working hours by an hour. According to the findings, planning for the erection work required 20.72 days and cost Rp. 136,082,784.72. The time acquired was 18.62 days and cost Rp. 137,751,475.31 with a time efficiency of 10.11% and additional costs of 1.23% after adding 1 hour of working hours. It took 10.37 days and cost Rp. 132,787,089.31 to add 2 units of mobile cranes Tadano TL-250e, which resulted in a time efficiency of 49.96% and a cost efficiency of 2.42%. It took 10.35 days and cost Rp 139,378,104.86 with the addition of 2 units of Kato KR-25H mobile cranes, with a time efficiency of 50.04% and additional costs of 2.42%.