In this paper, motor imagery EEG signals are preprocessed, using the state-of-the-art measurement and control software LabVIEW. Firstly, the elliptic filter is used for digital band-pass filtering. Then the soft-thresholding approach is adopted for wavelet denoising to enable programming with the BCI Competition 2005 dataset. The experimental results show that the method not only saves a lot of time in development and debugging, but also provides a good foundation for implementing a BCI system.