Abstract: Through the experiment and preliminary study about the anti-interference (including interferences caused by ambient temperature, humidity, ground vibration and air disturbance) of the observation cave of Taian Seismological station from November 1981 to October 1985, the following results are abtained: By means of the principle of inversion and dew point, a set of effective methods to reduce humidity in the cave are built up and the stability of ambient temperat-ure in the cave is increased;the microairflow in the cave is decreased.It has been proved that a moderately strong vibration on the earth surface nearby has hardly effect on the accuracy of instrumental records.Therefore the quality of observed data is improved and some quantitative and qualitatuve basis are provided for the processing of observed data.In addition, the authors also examine some air samples inside the cave and give some views regarding pollution of the environment which is under the condition of semi-airtight for a long time.