Water tube tiltmeters can clearly record information from long-period solid earth tides. However, because its natural period is long, it cannot respond to short-period tilt deformation, leading to the missing of short-term anomalous information. In this paper, the natural period of the instrument was reduced and the observation frequency band was expanded through mechanical structure optimization. Through use of sensors with higher precision and amplifier circuit, the signal-to-noise ratio of the instrument was improved, and normal observation of solid earth tide was ensured. By chitinous contrast observation, the difference in observation data after expansion of the frequency band was analyzed.