The signal exciting process of vibrator is well controlled and resulting signals are of high repeatability. In recent years，low frequency vibrator，for which the lowest frequency could be 1.5Hz，has been developed and shows its potential for subsurface structure exploring in regional scale. Detecting and enhancing extremely weak signal is the key for processing vibrator seismic signal at long distance. We evaluate different signal enhancing methods for multichannel seismic records excited by repeating low frequency vibrator，including stacking methods and separating methods. Compared with linear stacking，weighted stacking utilizes coherence of signal in multichannel records to suppress noise and enhance the signal-to-noise ratio(SNR)of stacking result. Semblance weighted stacking is more stable and effective than time-domain phase weighted stacking. Compared with time domain weighted stacking，time-frequency domain phase weighted stacking is capable of protecting signal frequency-band and the stacked signal is clearer. Signal value decomposition(SVD)can separate signal from multichannel records. In this experiment，the result of linear standard SVD separation is similar to linear stacking result. During the Anhui experiment of “Yangtze River Geoscience Project”，the low frequency vibrator excited repeatedly at two locations. We analyze different processing sequences after preprocess. The best sequence is first to detect signal by correlation for each excitation then enhance signal by time-frequency domain phase weighted stacking. Using repeated signal more than 200 times，clear Pg and Sg phase can be retrieved within 50km.