The soil in forest area is more complicated than the soil in farmland, and the performance structure of realtime measuring instrument of water content is more demanding, in order to improve the measurement performance and usability of the existing soil moisture sensor in the forest area, on the basis of optimizing the sensor structure, the conetype forest soil moisture sensor was designed based on standing wave principle. Cone angle was 30°, probe diameter was 20mm and probe length was 150mm. The transverse impact scope of the sensor was 10cm and vertical scope was 18cm, and the output linear fitting decision coefficient was over 0.96. Static and dynamic analysis showed that the measurement range of the sensor was from zero to saturated soil moisture content of clay soil, the measurement accuracy was 3%, the stability standard deviation was 0.49%, the overshoot was 0.48% and the transition time was 0.582s. The linear fitting determination coefficient of the measurement results was above 0.97 by comparing with TDR (TRIME-HD2, Germany), the results of the two measurements were basically the same, and the results showed that the designed sensor met the actual application requirements. But the designed sensor was more suitable for measuring soil moisture in the forest area and more convenient to use, it provided an effective means for forest tending and forest ecological monitoring.