Most of tipping bucket rain sensor faults have the feature of concealment. An optimized method of rainfall acquisition is introduced. Based on the operational principles of reed switches, the analysis of the abnormity in rainfall acquisition and the summarization of shortcomings of the current rainfall acquisition are conducted, and effective solutions are proposed to solve such problems as the failure of reed switches, the shifting resulted from the pulling in of two reed switches, and the sudden abnormal fragmentary rainfall and heavy rainfall, etc. The solutions include the diagnosis of the pulse width in the reed switch pulling in, the periodic diagnosis of the pulses of rainfall, measures to screen electromagnetic interference, and a new technique for diagnosing the long opening state of reed switches based on the trend analysis. Practice shows that these solutions are feasible and efficient to improve the credibility and accuracy of rainfall acquisition data.