This paper presents a new method for speech enhancement. It is well known that Wiener filtering is effective in reducing additive noises and the proposed method is based on it. This paper focuses on the design of Wiener filter, where we place emphasis on the recovery of original formant characteristics and the smooth transition of speech spectrum. Transformation method of LPC cepstrum vector extracted from noisy speech to reduce noise effects is given, which gives an estimated LPC cepstrum vector of original speech. Sharpening of formant peaks and eliminating false spectral peaks are necessary for high quality speech restoration and they are realized by the proposed method. Experiments of noise reduction have been performed, whose results show the effectiveness of the proposed method.