Oblivious transfer (OT) is an important basic cryptographic tool, which can be used in the constructions of many other cryptographic protocols, such as secure multi-party computation (SMPC) protocols, private information retrieval (PIR) and so on. The 1-out-of-n oblivious transfer (OT\+1\-n) setting involves two parties, the sender S and the receiver R. More specificly, the sender has n values and the receiver wants to obtain only one value from them. At the same time, the receiver’s choice is unknown to the sender and the receiver gets no extra information about the other values he doesn’t choose. In this paper, we firstly propose an efficient OT\+1\-n protocol based on the decisional Diffie-Hellman (DDH) hard problem assumption with full simulation in the standard malicious model. The full simulation means that the protocol can be simulated when the receiver and the sender are corrupted respectively under the ideal/real simulation paradigm, and also this is the highest security level in the standard stand-alone model. The idea behind the protocol mainly benefits from the dual-mode cryptosystem and the combination of zero-knowledge proof of knowledge (ZKPOK) of Diffie-Hellman tuples. The protocol has constant number of interactive complexity, and the computation and communication complexity is just liner of n.