This paper proposes a low complexity peak-to-average power ratio estimation scheme for OFDM systems. The new scheme introduces a non-equal-distance estimation based on triangle interpolation, which approximates higher oversampling samples by lower oversampling samples. Simulation shows the new scheme can achieve a good approximating to signal distribution of the real over-sampled OFDM signal. Furthermore, this estimation scheme is applied to conventional PAPR reduction schemes, such as PTS and SLM scheme. And simulation results show that the low complexity MSR scheme can achieve good PAPR reduction with much lower complexity.