The curing method becomes important to be considered in applying the Reactive Powder Concrete (RPC) in the field. Currently, the application of RPC in the field can be simulated with the method of steam curing at 90oC that resulted in compressive strength of 102 MPa. This study used some methods of curing included the method of steam curing at 90oC to investigate mechanical behavior of RPC such as compressive, flexural, and splitting tensile strengths. The objective of this research is to obtain the method of in-situ curing which reasonable good in results of the mechanical behavior of RPC. There were 4 types of curing method in this study, namely the steam curing method of 90oC for 8 hours in laboratory (C1), the water curing in laboratory (C2), the in-situ steam curing with flowed steam of 3 hours per day for 7 days (C3), and the in-situ wet curing (C4). This study showed that the compressive, flexural, and splitting tensile strengths of the RPC with in-situ curing method of type C3 compared with the RPC with curing method type C1 have the different of 10.6%, 19.0%, and 13.3%, respectively. The in-situ curing method of type C3 is better than the in-situ curing method of type C4 in term of the strengths.