Form document analysis is one of the most essential tasks in document analysis and recognition. One of the most fundamental and crucial tasks is the extraction of the reference lines which are contained in almost all form documents. This paper presents an efficient methodology for the complicated grey-level form image processing. We construct a non-orthogonal wavelet with adjustable rectangle supports and offer algorithms for the extraction of the reference lines based on the strip growth method using the multiresolution wavelet sub images. We have compared this system with the popular Hough transform (HT) based and the novel orthogonal wavelet based methods. As shown in the experiments, the proposed algorithmdemonstrates high performance and fast speed for the complicated form images. This system is also effective for the form images with slight skew.