The design method of very narrowband surface acoustic wave (SAW) filter with transverse structure is introduced in this paper. Through optimizing withdrawal weighting design, diffraction analysis and correction, and suppressing the wave guide effect by taking some effective measures, a SAW filter with very narrow band, good shape factor and high rejection has been fabricated. The insertion loss of filter is -21 dB, 1 dB relative band width is 1‰, out of band rejection is more than 50 dB, and passband ripple is 0.3 dB. The device has excellent comprehensive specifications.